Mouse Click can't work on OK button for Combo-Box selection

[lookingforK]

Hi experts,

I get a bizarre situation while I am using MS Access 2010 to select values with Combo Boxes on a form, i.e.:
* After I select one or more values from the drop-down list of a Combo Box, there is no response when clicking OK button using the mouse. It is stalled. I need to do the process again and then the mouse-click on OK button could work: click anywhere outside of the combo box, re-select the values, click OK Button, and done.

* However, I can always use Enter key (on the keyboard) upon OK button to complete the selection.

* The values in the drop-down list of the Combo Box were entered manually.




What is wrong with the Combo Boxes on the form? Why do I need to do twice to complete the selection using mouse-click? Why the keyboard-click ('Enter') can be always OK but not for the mouse-click?

Thank you in advance.

[June7]

Is this combobox bound to a multi-value field? I NEVER use multi-value field.

Do you want to provide db for analysis? Follow instructions at bottom of my post.

[lookingforK]

The problem was cause by using "Format Painter" to copy an existing combo-box (that has a conditional formatting) to this new one...