Microsoft Access 2003 VBA - Login Form - ms-access

Question

This is my first attempt to create a login form. I've read up a few forums about it and tried them myself. However, I've encountered the error when trying out the form.
"Run time error '2001': You canceled the previous operation."
Here's my code! The error highlighted is the DLOOKUP statement. When I move my cursor to LanID, it appears to be 0. (I guess it got something to do with it?)
Option Compare Database
Option Explicit
Private intLoginAttempts As Integer
Private Sub cmdLogin_Click()
'Check mandatory fields
If IsNull(Me.txtLanID) Or Me.txtLanID = "" Then
MsgBox "Lan ID is required.", vbOKOnly, "Required Data"
Me.txtLanID.SetFocus
Exit Sub
End If
If IsNull(Me.txtPassword) Or Me.txtPassword = "" Then
MsgBox "Password is required.", vbOKOnly, "Required Data"
Me.txtPassword.SetFocus
Exit Sub
End If
'Compare input password and database password
If Me.txtLanID <> "" Then
If Me.txtPassword = DLookup("Password", "tblUser", "[LanID]=" & Me.txtLanID) Then
LanID = Me.txtLanID
'Close Login Page
DoCmd.Close acForm, "frmUserLogin", acSaveNo
'Check whether user is an admin
If Me.txtAdmin = DLookup("Administrator", "tblUser", "[LanID]=" & Me.txtLanID) Then
If Me.txtAdmin = -1 Then
DoCmd.OpenForm "frmMenu"
Else
DoCmd.OpenForm "frmBack"
End If
End If
Else
MsgBox "Invalid Password. Try again.", vbOKOnly, "Invalid Entry!"
Me.txtPassword.SetFocus
End If
End If
'If user enters incorrect password 3 times
intLoginAttempts = intLoginAttempts + 1
If intLoginAttempts = 3 Then
MsgBox "You do not have access to the database. Please contact system administrator.", vbCritical, "Restricted Access!"
Application.Quit
End If
End Sub

Answer 1

If tblUser.LanID is text data type, enclose Me.txtLanID in quotes to avoid an error with your DLookup() expression. (You don't need .Value there because it's the default property.)
DLookup("Password", "tblUser", "[LanID]='" & Me.txtLanID & "'")
If that was not the explanation, test your DLookup() expression in the Immediate window (go there with Ctrl+g) to see whether it throws an error or what value it does return.
Note, when you test DLookup() in the Immediate window, use the current value of Me.txtLanID. For example, if Me.txtLanID contains the text "foo", test it like this ...
? DLookup("Password", "tblUser", "[LanID]='foo'")