Error Converting Data Type Nvarchar To Int

Hi,


I get "Error converting data type nvarchar to int." It is some kind of SQL exception. This is the code in my application.

SqlConnection sqlConnection1 = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);

SqlCommand cmd = new SqlCommand();



Object start;



string activityID = Session["activitygroupID"].ToString();

cmd.Parameters.AddWithValue("@ActivityGroupID", activityID);

cmd.CommandText = "get_startdate";

cmd.CommandType = CommandType.StoredProcedure;

cmd.Connection = sqlConnection1;

sqlConnection1.Open();



SqlDataReader reader = cmd.ExecuteReader(); //The code stops here!!!

start = reader["StartDate"];

sqlConnection1.Close();


The stored procedure on the SQL-server looks like so. StartDate is of DateTime type.


ALTER PROCEDURE [dbo].[get_startdate]

-- Add the parameters for the stored procedure here

@ActivityGroupID int

AS

BEGIN

SELECT StartDate

FROM dbo.CurrentGroup

WHERE ActivityGroupID = @ActivityGroupID

END


I appreciate any help!