Informix stored procedure does not execute an INSERT

CREATE PROCEDURE foo(p INT) RETURNING INT; 
  INSERT INTO bar VALUES(p); 
  RETURN 0; 
END PROCEDURE; 

RWDBStoredProc sp= db.storedProc(foo);
sp.execute();
 
 
 Cause
 
 
 We have observed that Informix stored procedures do not commit
 their results unless you be sure to read any result sets returned by
 that same stored procedure. What this means in the example above, 
is your DBTools application must read the returned result(s) if you 
wish the INSERT to be completed. Note that when this occurs 
you do not see an error returned from Informix, simply your INSERT 
does not execute. The reason DBACCESS works is because 
DBACCESS does retrieve the result. 
  
 

 
 
 Action
 
 
 If your stored procedure uses the statement  
RETURN

you must read the returned result(s) from your DBTools.h+ application. Here is a DBTools.h++ example showing how to read a stored procedure result.
RWDBStoredProc mySp= myDb.storedProc(foo); 
RWDBResult myResult = mySp.execute();
RWDBTable myResTable = myResult.table();
RWDBReader myRdr = myResTable.reader(); 
int myInt;
while(myRdr())
{
   myRdr >> myInt;
}

Or, if possible, removing the RETURN statement from your stored procedure should also fix it.