How to save a field calculated on a form to its table

[June7]

@Steve, that's it. Example right out of my procedure (ignore that I break normalization rules):

    If Not IsNull(![207.LabNum]) Then
        !frac1 = .tbxFrac1
        !frac2 = .tbxFrac2
    End If

[ssanfu]

@June, Looking at the example code, I see " !frac1". are you using something like

With Me.recordsource

 If Not IsNull(![207.LabNum]) Then
        !frac1 = .tbxFrac1
        !frac2 = .tbxFrac2
    End If

End With

[June7]

Not quite, just:

With Me
...
End With