I've never not known Forms!FormName!FieldName to work, that is odd.

Was the Customer Form open?

Wierd.  First thing that hits me is... Is the CustomerF Form open?

You didn't have quotes around it, did you?

And yes that 2nd notation is also handy because you can stick variables in that one.

CustomerF and ContactF were open and NO, typed exactly as shown. I played about for ages checking all these things before usinf Copilot, which came up with this as a last resort - which worked instantly!

That's weird. I've never had one notation work and not the other unless something was spelled wrong. I'd need to see the database to tell you exactly what happened. OR you have a corrupted database. Try compact & repair. Run down the troubleshooter.

Know I'm late to the party here, but life had me away a couple of weeks.  Also, I'll have to learn how you guys set text in these messages to fixed width highlighted when quoting code.

This is very strange, indeed.  I did a MsgBox test to get a field's value from another open form, and the "normal way" worked.  A couple of thoughts come to mind:
• You mentioned =Forms!CustomerF!EMail, perhaps the data type of whatever you are setting = to EMail is of a non-compatible type or encountered a null it is not liking?
• Perhaps give this a try:  Forms.CustomerF!EMail (my test worked with . or ! after Forms)
• If the Form is a continuous form type and has a header/footer section and the cursor is sitting in one of those areas, it wouldn't know which record it was "supposed" to be on

   I mention the additional cases if that so happened to be the case in the first trial, but was on an actual/different record when running Copilot's suggestion.

See Bang! v Dot.

Copilot and ChatGPT have been wrong about this kind of stuff many times because they're trained on public info on the Internet, including many forums, and we all know how many "experts" are out there.

If you're dealing with a continuous form, Access will return the value of the current record. Even if the cursor is sitting in a header or footer field, there's still a current record based on the record selector.

Richard Ahhhhh, 10-4.  Grazie for clarifying and the (.) vs (!) link as well.  It's been a little while since I had such a form w/ header/footer, since my Lockheed freight database days which was "eons" ago now.