Help about some basics

I have a form named « FormEntreemanquements »

I am trying to understand why I receive the message « impossible to find the form… » and the form will not open when I write the code this way :

Dim frmDocName As Form
Set frmDocName = Forms![FormEntreeManquements]
DoCmd.OpenForm frmDocName, acNormal, "", "", acFormEdit, acWindowNormal.

And why it works well when I write it this way :

Dim strDocName As String
strDocName = "FormEntreeManquements"
DoCmd.OpenForm strDocName, acNormal, "", "", acFormEdit, acWindowNormal

When should I declare the form one way or the other?

In what you are doing I wouldn't waste my time with your dec statements, just open your form

DoCmd.OpenForm "FormEntreeManquements"
, acNormal, "", "", acFormEdit, acWindowNormal

As for why, the docmd is look for a string value to identify the form name

S-