PROC Problem : Select for update

I have a problem when i try to lanch the following program :

   EXEC SQL PREPARE MyStmt FROM

       SELECT CHAMP1 FROM TAB1 WHERE CHAMP2="4" AND CHAMP3 = "C" FOR UPDATE;    EXEC SQL DECLARE MyCursor CURSOR FOR MyStmt;

   EXEC SQL OPEN MyCursor;

   EXEC SQL DESCRIBE MyStmt into q_APP;

   EXEC SQL FETCH MyCursor into :Var1;

   EXEC SQL CLOSE MyCursor;