Searching Where Form Variable Equals Data Field

I get a "data type mismatch error". I assume it is because this is a number, but I don't know what to change.

<%
dim cnStr
dim rcSet
dim frmSSN
dim sqlStr

'store form input into variables
frmSSN = Request.Form("SSN")

'create connection and recordset objects
Set cnStr = Server.CreateObject("ADODB.Connection")
Set rcSet = Server.CreateObject("ADODB.Recordset")

' defining database connection (connectionstring2.inc)
cnStr.ConnectionString = path
cnStr.Provider = provider
cnStr.open
%>

<%
SQL_query = "SELECT * FROM Orders WHERE Driver = '" & frmSSN & "'"
Set RS = cnStr.Execute(SQL_query)
WHILE NOT RS.EOF
%>