Interbase and Param as DateTime

Hi Everybody!
I've tried to port my IBX application to a DBX one, but I have a problem I
don't understand.
When I insert a statement with a param as a Date Time, I have "unassigned
code" as an error.

SQLQuery1.ParamByName('lm').AsDateTime := EncodeTime(12,12,12,12) +

With IBX, no problem at all. I have to say that I don't have the problem if
I use .AsDate or .AsTime.

Do you know why?