Add Record to Subform from Main Form - Getting Null Error on PK or duplicate PK

[user9]

I added an "Add Record" button to my main form. The Embedded Macro successfully creates a new record on the subform.
When I press any key any field I get the following error: "You tried to assign the Null value to a variable that is not a Variant data type".
When I click OK I can proceed, but why am I getting this error? What can I do to remove it (either with VBA or within the Embedded Macro)?

Alternately, I have found that creating the "Add Record" button in my subform creates a new record but my PK field gets populated with an existing value (the first PK value in my table). The subform shows two records, both the existing record with that PK and the new record with just the PK filled in.

Not sure which error is easier to resolve...

Thank you in advance!

[June7]

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