VBA - 'Object required' error message

Dear Experts,

Could you please have a look this short code part, briefly its target is assigning a button text (from SAP application) to a variable, but if there is no such button then going further:

ErrMes = session.findById("wnd[2]/usr/txtMESSTXT1").Text
Debug.Print ErrMes
If ErrMes Is Nothing Then
    GoTo NoChangeMessage
Else
    ErrMes = session.findById("wnd[2]/usr/txtMESSTXT1").Text
    If InStr(1, ErrMes, "change", vbTextCompare) > 0 Then
    session.findById("wnd[2]/tbar[0]/btn[0]").press
    End If
End If

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Actually it has the issue that the ErrMes variable got a value (as Debug.Print shows 'No changes were made' text assigned to it from the button), but then the VBA script stops at line

If ErrMes Is Nothing Then

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with error message:

Run-time error '424'
Object required


Could you please advise what is the nature of the issue there and eventually how to eliminate?

Thanks in advance,