I Only Get The First Character Of The Field Returned .. What Am I Doing Wrong ?

 
here is my business/data object  for some reason I only get the first character back,  say value is Charlie, I only get C  public string GetUserName(long UserId)
{
try
{
string userName;

DiscussionDB data = new DiscussionDB();
List paramlist = new List();
paramlist.Add(data.CreateParameter("@UserId", UserId));
paramlist.Add(data.CreateParameter("@UserName", "", ParameterDirection.Output, DbType.String, 20));
data.ExecuteNonQuery("dbo.Discussion_User_Name", ref paramlist);
userName = paramlist[1].Value.ToString();


return userName;
}
catch
{
throw;
}
}




ALTER PROCEDURE [dbo].[Discussion_User_Name]
@UserId bigint,
@UserName varchar(20) output
AS
SET NOCOUNT ON


SET @UserName = (Select [Name] from Discussion_Member WHERE UserID = @UserID)

if (@UserName is null or @UserName = '')
BEGIN
SET @UserName = (Select UserName from Membership_User WHERE UserID = @UserID)
END