Function StartLog(LogName$)
Local File As Integer
Local Offset As Integer
Repeat
Inc File
Until Not( File Open(File) )
If Path Exist("Data\Logs\") = 0 Then Make Directory "Data\Logs\"
If Path Exist("Data\Logs\") and File Exist("Data\Logs" + Logname$ + " .txt" )
Open to Read File, "Data\Logs\" + Logname$ + ".txt"
Offset = File Size("Data\Logs\" + Logname$ + ".txt")
Else
Open to Read File, "Data\Logs\" + Logname$ + ".txt"
EndIf
Endif
EndFunction
There were some errors in your code...
Now as a note, I don't know what the Global Values you're using to keep the FileID and FileOffset are; or why when you're opening to read you even need said offset., where-as open to write this would make sense as you'd want to continue the log at the end of the existing file.
That should solve the immediate issues with the function; but it still seems a little odd in how it's written (at least to me).
I'm not sure what information / how you're logging info though... so without that I can't really write a replacement.
In any case from the errors it seems like you have 2 References to "StartLog" (be that as variables or functions) ... so checking your include file for more than one instance might be a good idea.