Storedproc (again Sorry)

I get a execption when i run my code i dont know how to debug sql statements so ya could any one give me adive heres the code
 
 public static int CreateMember(string username, string aspApplicationName)
{
int returnvalue = 0;
DateTime dateCreated = DateTime.Now;

// All users are added to users role upon registration.
Roles.AddUserToRole(username, "Users");

String connectionString = ConfigurationManager.ConnectionStrings["SqlConn"].ConnectionString;
SqlConnection conn = new SqlConnection(connectionString);
SqlCommand command = null;
try
{
conn.Open();
command = new SqlCommand("InsertMember", conn);
command.CommandType = CommandType.StoredProcedure;
command.Parameters.Add(new SqlParameter("@AspNetUsername", username));
command.Parameters.Add(new SqlParameter("@AspNetApplicationName", aspApplicationName));
command.Parameters.Add(new SqlParameter("@DateCreated", dateCreated));
SqlParameter sqlParam = command.Parameters.Add("@Id", SqlDbType.Int);
sqlParam.Direction = ParameterDirection.ReturnValue;
command.ExecuteNonQuery();
returnvalue = (int)command.Parameters["@id"].Value;
conn.Close();

}
catch (Exception ex)
{

}
finally
{
if (command != null)
command.Dispose();
if (conn != null)
conn.Dispose();
}
return returnvalue;
}  i get a exception at
command.ExecuteNonQuery(); and if i dont do int returnvalue = 0; it says i cant use it cause it hasnt be initialized or something like that 
ALTER PROCEDURE [dbo].[InsertMember]
    @AspNetUsername nvarchar(256),
    @AspNetApplicationName nvarchar(256),
    @DateCreated smalldatetime = getdate
AS
DECLARE @Id int;
SET NOCOUNT ON;
INSERT
INTO [Members] ([AspNetUsername], [AspNetApplicationName],
[DateCreated]) VALUES (@AspNetUsername, @AspNetApplicationName,
@DateCreated);
SET @Id = @@IDENTITY
SELECT  @Id  AS [Id] theres my stored proc any ideas?