Default value won't show up!

[summer]

I have many fields set up to have a default value of 0. The properties I set up are:

Format: Standard
Decimal Places: 2
Default Value: 0

My problem is that some of the fields aren't showing the 0. I've also tried changing the Format to Fixed and General. Is there anything I can do? I need the default value because the fields are being added together and they won't add together if some of the fields are blank.
Thanks.

 

[summer]

I think I'm getting somewhere. The fields that are not showing the default value are linked to combo boxes. Sometimes, the combo box may not be selected. The following is my expression:

Private Sub Combo166_AfterUpdate()
Me.LBS_GAL10 = Me.Combo166.Column(1)
DoCmd.RunCommand acCmdRefresh

End Sub

How would I add to this telling it to default to 0 of no entry is made?