problem with code attached to a login form

[Jhonny]

I've created a login form which I am trying to implement
but I get an error I've never seen. It says "You have
cancelled the current operation" Here is what my code
looks like:

Private Sub cmdLogin_Click()

'Check to see if data is entered into the UserName combo
box

If IsNull(Me.cboEmployee) Or Me.cboEmployee = "" Then
MsgBox "You must enter a User Name.",
vbOKOnly, "Required Data"
Me.cboEmployee.SetFocus
Exit Sub
End If

'Check to see if data is entered into the password box

If IsNull(Me.txtPassword) Or Me.txtPassword = "" Then
MsgBox "You must enter a Password.",
vbOKOnly, "Required Data"
Me.txtPassword.SetFocus
Exit Sub
End If

'Check value of password in tblEmployees to see if this
matches value chosen in combo box

If Me.txtPassword.Value = DLookup
("strEmpPassword", "tblEmployees", "[lngEmpID]=" &
Me.cboEmployee.Value) Then

lngMyEmpID = Me.cboEmployee.Value

'Close logon form and open splash screen

DoCmd.Close acForm, "frmLogon", acSaveYes
DoCmd.OpenForm "EnterNew Order Data Sheet1"

Else
MsgBox "Password Invalid. Please Try Again",
vbOKOnly, "Invalid Entry!"
Me.txtPassword.SetFocus
End If

'If User Enters incorrect password 3 times database will
shutdown

intLogonAttempts = intLogonAttempts + 1
If intLogonAttempts > 3 Then
MsgBox "You do not have access to this database.
Please contact your system administrator.",
vbCritical, "Restricted Access!"
Application.Quit
End If

End Sub

-The error highlights my DLookup function and says "you
have cancelled the current operation. Does anybody know
why or what is wrong with it?

Thanks in advance