call IFS pslq method return to field

sFormName = ":i_hWndFrame." + Ifs.Fnd.ApplicationForms.Int.QualifiedItemNameGet(this);
sStmt = "BEGIN\r\n" +
        "&FORM.nHandlingUnitCount := &AO.C_Terminal_Data_Util_API.Count_Handling_Units( &FORM.dfsContract,\r\n" +
        "&FORM.dfPartNo);\r\n" +
        "END";
 IF (DbPLSQLBlock(cSessionManager.c_hSql, Vis.StrSubstitute(sStmt, "&FORM", sFormName)))