Run time error 3061

[beaurou]

Thanks you

it Work fine,

I try to change m_intDrawntype as String but it give me runtime error 94 Invalid use of Null, so I when back to m_intDrawntype as variant

[orange]

Post a copy of your database so that readers can see the bigger picture.
Remove anything private/confidential.
Do a compact and repair , then zip.

[beaurou]

This is the Database

Main form is Form1

[rpeare]

You are opening the form form2 then running the code you're running so form 2 will ALWAYS open.

You need to perform this check on FORM1 *before* you open any other forms, then based on the retrieved value open the appropriate form.

on your form FORM1 remove the embedded macro from your button and use

If IsNull(DLookup("[Drawing_Type]", "[FileA MAPPS]", "[Signal_ID] = '" & Forms!form1!Text4 & "'")) Then    
    DoCmd.OpenForm "form2"
Else
    DoCmd.OpenForm "form3"
End If

instead.

Also remove the form opening commands from FORM2 or you will continue to see form3 opened as well.