HELP! I have typed the code as follows (7:35 in tutorial) but when I test it with the correct pairing of Username and Password, I get "Runtime Error 94" Invalid use of Null and the debug takes me to the X= line of code.  

I am using Access 2010 - should that make a difference?

My code reads:
Private Sub Login_Click()
    If IsNull(txtUsername) Then
        MsgBox "Invalid UserName"
        Exit Sub
    End If
    If IsNull(txtPassword) Then
        MsgBox "Invalid Password"
        Exit Sub
    End If

Dim X As Long
X = DLookup("UserID", "UserT", "UserName='" & txtUsername & "'AND Password='" & txtPassword & "'")

MsgBox X
DoCmd.Close acForm, "LoginF"

End Sub

---

Reply from Richard Rost:

I used 2007 in the class, and the two are pretty much identical, but DLOOKUP can sometimes throw up errors like this. Just enclose it inside of some error handling:

Dim X As Long
X = ""
on error resume next
X = DLookup("UserID", "UserT", "UserName='" & txtUsername & "'AND Password='" & txtPassword & "'")
on error goto 0

That will turn off the error message, and X will remain "" if nothing was looked up.