You can usually read the values of controls in the on-open event, but you
CAN NOT modify values.
The on-open event of a form has a "cancel" feature, and if you set cancel =
true, then the form does not load.
So, on-open, is really for checking values, and things that *could* allow
you to change your mind if the form is to be opened (for, example, if the
record is locked by somene else..you could display a message..and the form
would NOT load).
So, once your checking/testing code to allow the form to open is completed,
then any code that sets up the forms values, defaults and initialize your
variables etc belongs in the forms on-load event..NOT the on open. On open
is too soon to start playing with, and modifying values..and further..the
on-open event is not for setup and initializing code anyway.
So...move your code stuff to on-load.....