Forms :: Unable To Set Password Protection On A Combobox

I am trying to set password protection on a combobox where there are only a few people who I want to be able to select their name to provide authorisation. I found the below code on a website and modified it slightly for my table (tbl_Approval) that contains two fields; Approver and Password. I can see how the code is supposed to work however I keep getting a syntax error (missing operator) in query expression on line: Set rs = CurrentDb.OpenRecordset(sql).

Code:
Private Sub Approved_By_Enter()
Dim pwd As String
Dim rs As Object, rstable As Object, count As Integer, counter As_ Integer
Dim sql As String, recount As Integer
sql = "SELECT * " & "FROM [tbl_Approval] " & "WHERE [Approver]= " & Me.Approved_By
Set rs = CurrentDb.OpenRecordset(sql)

[Code]...