Have you tried using @error/@serror to see why it is not deleting the file?

Code:

$file=DIR("\\server\adlogs\logs_dc1\*.log")
WHILE $file <> "" and @error=0
 $c=$c+1
 ? $file
 if DateCalc(@date,left(getfiletime($file),10)) > 2 
  ? $file 
  del "\\monm607\adlogs\monm_dc1\$file"
  ? @serror
 endif 
 $file=DIR()
LOOP