Verify Password/Login Userform to worksheet Help

I am trying to create a log-in page on a userform, frmlogin in "sheet3."
The userform is simply a textbox, Username (txtuser) and a textbox, Password (txtpass).
Command Button is cmdcheck

I want the User to enter their username and password and for my macro to verify that they match referencing data in a seperate worksheet, (Sheet6).

Upon verification I want the user to be unloaded on "sheet1"

I am currently getting this message:
"unable to get vlookup property of the worksheetfunction class"

I am new to vba and have spent way too much time on this one small issue. Please help me someone!!!!

Private Sub cmdcheck_Click()
Dim Username As String
Username = txtuser.Text
Dim password As String
password = txtpass.Text


'Check to see if data is entered into field: txtUserNameIn
If IsNull(Me.txtuser) Or Me.txtuser = "" Then
MsgBox "You must enter your username.", vbOKOnly, "Required Data"
Me.txtuser.SetFocus
Exit Sub
End If

'Check to see if data is entered into field: txtPasswordIn
If IsNull(Me.txtpass) Or Me.txtpass = "" Then
MsgBox "You must enter your Password (case sensitive).", vbOKOnly, "Required Data"
Me.txtpass.SetFocus
Exit Sub
End If

'Check to see if the Username & Password entered is a valid username in the 'User Register'
'****************
If Username = WorksheetFunction.VLookup(Me.txtuser.Value, Range("pass"), 2, 0) Then
'****************
If password = WorksheetFunction.VLookup(Me.txtuser.Value, Range("pass"), 3, 0) Then
MsgBox "Password & Username Accepted"
Unload Me
Sheets("landing").Select
Range("A1").Select
Else
MsgBox "Username & Password Combination Not Accepted"
Unload Me

End If
End If

End Sub

Shelton,
Thank You for jumping in and helping! I am now getting "Subscript out of range" and my Set ul = Sheets("Sheet6") is being highlighted.

I think it is because sheet6 is not the active worksheet. Any ideas on how to remedy this?


-Jeff