I cannot reproduce the [unknown function] message with the code you provided.
I tried creating a single button and still get the same error. Here's the entire code (very long sorry). It's based on Habla's settings.
// Original code by necropimp, modified by AstreaEdge, final by KockRoach
// Appearance changed by Habla. Muchas gracias to those above!
// Best viewed with vert pad 10, hor pad 13, line space 2, Segoe UI 7pt font, black background
// !!!!BEGIN USER CONFIGURATION!!!!
// Show Artist? (1 = show, 0 = don't show)
$puts(arts,1)
// Show Album?
$puts(albs,1)
// Show Title?
$puts(tils,1)
// Info Heading Color e.g. "Title:"
$puts(head,$rgb(61,129,193))
// Info Color e.g. "Black Dog"
$puts(info,$rgb(255,255,255))
// Info Annotation Color (e.g. kbps is the annotation)
$puts(anno,$rgb(255,255,255))
// Separator
// the separators (Song,Play,Tech info) will change to a different color if the panel mode is set to Follow cursor.
// change "followcursorcol" to change this color. It is currently set to flash orange.
$puts(followcursorcol,$rgb(200,150,50))
$puts(text2,$rgb(255,255,255))
$puts(text1,$if(%_trackinfo_nowplaying%,$rgb(61,129,193))$if(%_trackinfo_followcursor%,$get(followcursorcol)))
$puts(fadeend,$rgb(0,0,0))
$puts(seplen,83)
$puts(sepchar,'.')
// Set Rating character
$puts(ratingchar,'?')
// !!!!END USER CONFIGURATION!!!!
// Day Conversion
$puts(day,$substr(%last_played%,9,10))
$if(%last_played%,
$if($strcmp($left($get(day),1),0),$puts(day,$right($get(day),1))))
$if($strcmp($get(day),11),$puts(xx,th),
$if($strcmp($get(day),12),$puts(xx,th),
$if($strcmp($get(day),13),$puts(xx,th),
$if($strcmp($right($get(day),1),1),$puts(xx,st),
$if($strcmp($right($get(day),1),2),$puts(xx,nd),
$if($strcmp($right($get(day),1),3),$puts(xx,rd),
$puts(xx,th)))))))
// Month Conversion
$puts(month,$substr(%last_played%,6,7))
$puts(month_name,$select($get(month),
Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec))
// Year Conversion
$puts(year,$substr(%last_played%,1,4))
// Time Conversion
$puts(hour,$substr(%last_played%,12,13))
$puts(min,$substr(%last_played%,14,16))
$puts(sec,$substr(%last_played%,17,19))
// 24 Hour to 12 Hour Conversion
$if($strcmp($left($get(hour),1),0),$puts(hour1,$right($get(hour),1)))
$if($strcmp($left($get(hour),1),1),$puts(hour1,$sub($get(hour),12)))
$if($strcmp($left($get(hour),1),2),$puts(hour1,$sub($get(hour),12)))
$if($strcmp($get(hour),00),$puts(hour1,12))
$if($strcmp($get(hour),10),$puts(hour1,10))
$if($strcmp($get(hour),11),$puts(hour1,11))
$if($strcmp($get(hour),12),$puts(hour1,12))
// AM/PM Conversion
$if($strcmp($get(hour),00),$puts(yy,am))
$if($strcmp($get(hour),10),$puts(yy,am))
$if($strcmp($get(hour),11),$puts(yy,am))
$if($strcmp($get(hour),12),$puts(yy,pm))
$if($strcmp($get(hour),24),$puts(yy,am))
$if($strcmp($left($get(hour),1),0),$puts(yy,am))
$if($strcmp($left($get(hour),1),1),$puts(yy,pm))
$if($strcmp($left($get(hour),1),2),$puts(yy,pm))
// Date Format
$puts(time_of_year,$get(month_name) $get(day)$get(xx)',' $get(year))
// Time Format
$puts(time_of_day,$get(hour1)$get(min)$get(sec) $get(yy))
// SONG INFO SEPARATOR
$transition($repeat($get(sepchar),$get(seplen)),$get(fadeend),$get(text1))$get(text1)'[' $get(text2)S o n g I n f o $get(text1)']'$char(10)
$if($strcmp(1,$get(tils)),$if(%title%,$get(head)Title: $get(info)%title%[ $char(40)%version%$char(41)]$char(10),),)
$if($strcmp(1,$get(arts)),$if(%artist%,$get(head)Artist: $get(info)%artist%$char(10),),)
$if($strcmp(1,$get(albs)),$if(%album%,$get(head)Album: $get(info)%album%[ $char(40)%subtitle%$char(41)][ $char(91)%edition%$char(93)]$char(10),),)
$if(%disc%,$get(head)Disc: $get(info)%disc%$get(head)$if(%disc%, of $get(info)%totaldiscs%)$char(10),)
$if(%date%,$get(head)Year: $get(info)%date%$char(10),)
$if(%tracknumber%,$get(head)Track #: $get(info)%tracknumber%$char(10),)
$transition($repeat($get(sepchar),$get(seplen)),$get(text1),$get(fadeend))$char(10)
$if(%genre%,$get(head)Genre: $get(info)%genre%$char(10),)
$if(%style%,$get(head)Style: $get(info)%style%$char(10),)
$if(%mood%,$get(head)Mood: $get(info)%mood%$char(10),)
$if(%tempo%,$get(head)Tempo: $get(info)$select(%tempo%,Freeflow,Slow,Medium,Fast,Frenetic,Choose between 1-5)$char(10),)
$if(%bpm%,$get(head)BPM: $get(info)$num(%bpm%,1)$char(10),)
$if(%rating%,$get(head)Rating: $repeat($get(info)$get(ratingchar),%rating%)
$repeat($rgb(70,70,70)$get(ratingchar),$sub(5,%rating%))$char(10),)
// TECH INFO SEPARATOR
$transition($repeat($get(sepchar),$get(seplen)),$get(fadeend),$get(text1))$get(text1)'[' $get(text2)T e c h I n f o $get(text1)']'$char(10)
$get(head)Length: $get(info)$if(%_length%,%_length%,)$if(%_isplaying%, / %_time_elapsed%$get(anno)$if(%_length%, / -%_time_remaining%),%_length%)$char(10)
$get(head)Type:$if(%__codec%, $get(info)%__codec%) $get(info)
$if2(%__bitrate_dynamic%,%__bitrate%) $get(anno)Kb/s $if($stricmp(%__codec%,mp3),$if($stricmp(%__extrainfo%,vbr),VBR,CBR))
$char(10)
$if(%__lame_version%,$get(head)Preset: $get(info)$left(%__lame_version%,4) $right(%__lame_version%,4) [$upper(%__lame_profile%)]$char(10),)
$if(%__flac_vendor%,$get(head)Encoder: $get(info)$if($stricmp(%__flac_vendor%,reference libFLAC 1.1.2 20050205),FLAC 1.1.2 -8)$char(10),)
$if(%__mpc_profile%,$get(head)MPC Profile: $get(info)%__mpc_profile%$char(10),)
$get(head)Compression: $get(info)$div(1411,%__bitrate%).$substr($muldiv(1411,100,%__bitrate%),2,3):1 '('$get(info)$muldiv(%__bitrate%,100,1411)$get(anno)'%)'$char(10)
$get(head)Channels: $get(info)$if($stricmp($codec(),MP3),$get(space2)$caps(%__mp3_stereo_mode%),
$if(%__channels%,$ifgreater(%__channels%,1,Stereo,Mono),'?'))$char(10)
$if(%__bitspersample%,$get(head)Bitdepth: $get(info)%__bitspersample% bits/sample$char(10),)
$if(%__samplerate%,$get(head)Samplerate: $get(info)$div(%__samplerate%,1000).$substr(%__samplerate%,3,3) KHz $char(10))
$if(%__replaygain_album_gain%,$get(head)Replay Gain: $get(info)A,$if(%__replaygain_track_gain%,$get(head)Replay Gain: $get(info)T,$get(head)Replay Gain: $rgb(255,0,0)X))$char(10)
$transition($repeat($get(sepchar),$get(seplen)),$get(text1),$get(fadeend))$char(10)
$if(%path%,$get(head)Path: $get(info)%path%$char(10),)
$if(%_filesize%,$get(head)Filesize: $get(info)
$div(%_filesize%,1048576).$left($num($muldiv($mod(%_filesize%,1048576),100,1048576),2),2) $get(anno)'MB'$char(10),)
$if(%last_played%,
// PLAY STATS SEPARATOR
$transition($repeat($get(sepchar),$get(seplen)),$get(fadeend),$get(text1))$get(text1)'[' $get(text2)P l a y I n f o $get(text1)']'
$char(10),)
$if(%play_count%,$get(head)Played: $get(info)%play_count% times$char(10),)
$if(%last_played%,$get(head)Last played on: $get(info)$get(time_of_year) at $get(time_of_day)$char(10),)
$get(head)$progress(%_time_elapsed_seconds%,%_time_total_seconds%,52,$get(info)'()',$get(head)'-')
$get(info)$muldiv(%_time_elapsed_seconds%,100,%_length_seconds%)'%'$char(10)
$if(%mood%,,
// MOOD BUTTONS
$transition($repeat($get(sepchar),$get(seplen)),$get(fadeend),$get(text1))$get(text1)'[' $get(text2)S e t M o o d $get(text1)']'
$char(10)
$button2(0,0,0,0,$calcwidth(Properties),13,'$font(tahoma,8,,0-0-0)Properties','$font(tahoma,8,underline,0-0-0)Properties', properties,))
[!--sizeo:1--][span style=\"font-size:8pt;line-height:100%\"][!--/sizeo--]Edit: Changed CODE to CODEBOX.[/size]