...Already a data reader associated...

[Jesse]

I'm getting the error, "There is already an open DataReader associated with 
this Connection which must be closed first." when I close a DataReader. 
Here's the code:

Cmd = New MySQLCommand("SELECT AddPayment(" & _
   "'" & MySQLDateTime(Now) & "'," & _
   "'" & MySQLDateTime(Now) & "'," & _
   "'" & Replace(CardType.SelectedValue,"'","''") & "'," & _
   "'" & InvNo.Text & "'," & _
   "''," & _
   cTotal & "," & _
   "'') As PayID",Conn)
RS=Cmd.ExecuteReader()
if RS.Read then
   cPID = RS("PayID").ToString
end if
RS.Close // ERROR OCCURS HERE
RS=Nothing

AddPayment() us a function:

CREATE DEFINER = 'root'@'localhost' FUNCTION `AddPayment`(dPayDate DATETIME, 
dDepositDate DATETIME, cPayType varchar(20), cInvNo varchar(7), cCheckNo 
varchar(20), nAmount double(10,2), cNotes TEXT)
    RETURNS int(11)
    DETERMINISTIC
    CONTAINS SQL
    SQL SECURITY DEFINER
    COMMENT ''
BEGIN
   INSERT INTO Payments 
(PayDate,DepositDate,PayType,InvNo,CheckNo,Amount,Notes) VALUES
      (dPayDate, dDepositDate, cPayType, cInvNo, cCheckNo, nAmount, cNotes);
   RETURN LAST_INSERT_ID();
END;

If this were truely a "..already has a datareader associated.." error, then 
it would occur on the "Cmd.ExecuteReader()" line, not the RS.Close line, so 
I believe that this error doesn't really mean what it says.

Does anyone have any clues on this?

Thanks,
Jesse