Stored procedure problem!

This should be an easy one!

I have a table called "renewal", which has a field called "owing" of type varchar(10). The owing field contains only numbers (some of them have decimals). I created a stored procedure called sp_count2 which finds the sum of the "owing" field. The stored procedure works.

The problem is when I call the stored procedure from a web page, I can't retrieve the sum if I set the total variable to type float. If I set it to adInteger, then it returns an integer.

If I set it to adFloat or adNumeric, I get this error:

ADODB.Parameters error '800a0e7c'
The application has improperly defined a Parameter object.

Here's the stored procedure:

CREATE PROCEDURE sp_count2
   @out_renewal_total float OUTPUT
AS
declare @q_renewal_total float

Select @q_renewal_total = Sum(Convert(float(10,2), owing))
From renewal

select @out_renewal_total = @q_renewal_total
GO

Here's the ASP page:

<%
Dim renewal_total

Call get_count()

Function get_count()

   Dim conn
      
   set conn = Server.CreateObject("ADODB.Connection")
   conn.Open "dsn"

   ' find total counts for this year
   Call calc_count(conn, renewal_total)

   conn.Close
   Set conn = Nothing

End Function


' Calculate total revenue
Sub calc_count(con, renew_total)

   Dim cmdCount
      
   Set cmdCount = Server.CreateObject("ADODB.Command")
   cmdCount.CommandText = "sp_count2"

   cmdCount.ActiveConnection = con
   cmdCount.CommandType = adCmdStoredProc

   cmdCount.Parameters.Append    cmdCount.CreateParameter("out_renewal_total", adInteger, adParamOutput)

   cmdCount.Execute

   renew_total = cmdCount.Parameters("out_renewal_total")
      
   Set cmdCount = Nothing

   Response.Write "total: " & renew_total & "<BR>"

End Sub      

%>