The value that you are specifying for the insert is fine, it is the form element that you are validating that is the problem. Instead of referring to it as $_POST["Log_in_group_File"] you should refer to it as $_FILES["Log_in_group_File"]. Try updating line 24 to be like this:
$WAFV_Errors .= WAValidateRQ((isset($_FILES["Log_in_group_File"])?$_FILES["Log_in_group_File"]:"") . "",true,3);
I think this will get it working correctly for you.