ms sql in ASP (Classic) Parameter error

ms sql in ASP (Classic) Parameter error

I keep getting an error saying the command Parameters is not valid, how
can I fix this problem? Thanks.
' OPEN DATABASE
dim objConn, strQuery
dim strConnection
set objConn = Server.CreateObject("ADODB.Command")
objConn.ConnectionString = "Driver={SQL Server Native Client
11.0};Server=Master-PC\NMSSQL;Trusted_Connection=no;UID=VISITORDB;PWD=testPWD;database=testDB;"
objConn.Open strConnection
dim objDupCheck
set objDupCheck = Server.CreateObject("ADODB.Command")
set objDupCheck.ActiveConnection = objConn
strQuery = "SELECT * from CHECKS where CHECK_NO = ?"
objConn.Parameters(0) = Request.Form("txtCheckNo")
objDupCheck.Open strQuery
if objDupCheck.EOF then
objDupCheck.Close
end if