I created a stored procedure:

CREATE PROCEDURE SideCheckUpdate(IN :vSU_ID INTEGER, IN :vBoardThick INTEGER, IN :vComp_ID INTEGER);
BEGIN

DECLARE :vNumberOfSides INTEGER;
SELECT Quantity INTO :vNumberOfSides FROM WO_UNITCOMPONENTS WHERE SU_ID = :vSU_ID AND Comp_ID = 0;

IF (:vNumberOfSides > 0) THEN
UPDATE WO_UNITCOMPONENTS SET WO_UNITCOMPONENTS.Clength = (SELECT WO_UNITS.TOTAL_Width - (:vBoardThick * :vNumberOfSides) FROM WO_UNITS Where UnitCode = WO_UNITS.Code) WHERE WO_UNITCOMPONENTS.Comp_ID = :vComp_ID;

ELSE
UPDATE WO_UNITCOMPONENTS SET WO_UNITCOMPONENTS.Clength = (SELECT WO_UNITS.TOTAL_Width FROM WO_UNITS Where UnitCode = WO_UNITS.Code) WHERE WO_UNITCOMPONENTS.Comp_ID = :vComp_ID;

END IF;

END;

The update before the ELSE create an error "ODBC Error: SQLSTATE = S1000, Native error code = -5099
Error in expression: WO_UNITS . TOTAL_Width - ( :vBoardThick * :vNumberOfSides ) " but if I substitute the variables ( :vBoardThick * :vNumberOfSides ) with integers (16 * 2) it works.

What can I do?