VBA VLookup Error 1004

Hi All,

Im trying to create a userform in VBA in which I can manually enter a number in a textbox which then will search for the corresponding data in a different sheet.

Private Sub textNumber_Change()

Dim Number As Integer
Dim Costumer As String

Number = textNumber.Value

Costumer = Application.WorksheetFunction.VLookup((textNumber.Value), [sheet4!A2:Z18], 2, False)
labelCostumer.Caption = "Costumer: " & Costumer

When I try this, I get error 1004; "The properties of Vlookup of WoksheetFunction cannot be executed".

What am I doing wrong and how to fix this?

Thanks in advanced!!