How to make record in form not return #error when it can't find a default value

[oatsybob]

I have a form to input information about correspondences between my organization and our partners. I've linked these data with two other tables: one that lists general information about the organizations and one that lists information about specific contacts within a particular organizations. For my input form about correspondence history, I've set the default values of the two fields that have relationships with the primary keys from these two other tables to pull values from two list boxes on another form. The problem is that in some situations, I want to input a correspondence history for an organization that I don't want to associate with a particular contact. In these cases, the record in my form returns #Error, because it's looking for a default value in a list box but not finding it. Is there a way to make the record return null instead of an error?

Thanks

[June7]

You have the DefaultValue property referencing listbox on a form? That form must be open.

[oatsybob]

It is open. And it works fine when an item in the listbox is selected, but when there isn't it returns #Error

[June7]

The textbox is bound to field? Is empty string allowed in table? (I don't allow empty strings in tables.)

I just tried setting DefaultValue in table to a control and it doesn't work.

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