change this line:
$WAFV_Errors .= WAValidateRQ((isset($_POST["Contact_Form_group_Sample_FIle_Upload_MB_Max_size"])?$_POST["Contact_Form_group_Sample_FIle_Upload_MB_Max_size"]["name"]:"") . "",false,5);
to:
$WAFV_Errors .= WAValidateRQ((isset($_FILES["Contact_Form_group_Sample_FIle_Upload_MB_Max_size"])?$_FILES["Contact_Form_group_Sample_FIle_Upload_MB_Max_size"]["name"]:"") . "",false,5);