diff --git a/modules/Students/Student.php b/modules/Students/Student.php
index d9f66cdf0..aefbd3f61 100644
--- a/modules/Students/Student.php
+++ b/modules/Students/Student.php
@@ -202,15 +202,19 @@
 		}
 		elseif (!isset($error)) //new student
 		{
-			if ( ( $student_id = filter_input( INPUT_POST, 'assign_student_id', FILTER_VALIDATE_INT ) ) > 0 )
+			if ( isset( $_REQUEST['assign_student_id'] )
+				&& $_REQUEST['assign_student_id'] !== '' )
 			{
-				if(count(DBGet(DBQuery("SELECT STUDENT_ID FROM STUDENTS WHERE STUDENT_ID='".$student_id."'"))))
+				if ( ( $student_id = filter_input( INPUT_POST, 'assign_student_id', FILTER_VALIDATE_INT ) ) > 0 )
 				{
-					$error[] = sprintf(_('That %s ID is already taken. Please select a different one.'),Config('NAME'));
+					if(count(DBGet(DBQuery("SELECT STUDENT_ID FROM STUDENTS WHERE STUDENT_ID='".$student_id."'"))))
+					{
+						$error[] = sprintf(_('That %s ID is already taken. Please select a different one.'),Config('NAME'));
+					}
 				}
+				else
+					$error[] = _('Please enter valid Numeric data.');
 			}
-			else
-				$error[] = _('Please enter valid Numeric data.');
 
 			//hook
 			do_action('Students/Student.php|create_student_checks');