Stored procedure doesn't return output - asp.net

Question

I have a simple stored procedure which inserts a users record in a table and should give out its userid.
Here is the stored procedure:
Alter proc spRegistration
#UserId nvarchar(10) output,
#Name nvarchar(20),
#EmailAdd nvarchar(20)
as
begin
Declare #Count int;
Declare #ReturnCode int
Select #Count = Count(EmailAdd)
from tblAllUsers
where EmailAdd = #EmailAdd
if #Count > 0
begin
Set #ReturnCode = -1
end
else
begin
Set #ReturnCode = 1
Insert into tblAllUsers(Name, EmailAdd)
values(#Name, #EmailAdd)
end
Select #UserId = UserId
from tblAllUsers
where EmailAdd = #EmailAdd
Select #ReturnCode as ReturnCode
end
I try to get the userid into a textbox like below :
string CS = ConfigurationManager.ConnectionStrings["hh"].ConnectionString;
using (SqlConnection con = new SqlConnection(CS))
{
con.Open();
SqlCommand cmd = new SqlCommand("spRegistration", con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#Name", txtName.Text);
cmd.Parameters.AddWithValue("#EmailAdd", txtEmailAddress.Text);
var UserID = cmd.Parameters.AddWithValue("#UserId", SqlDbType.NVarChar);
UserID.Direction = ParameterDirection.Output;
int ReturnCode = (int)cmd.ExecuteScalar();
if (ReturnCode == -1)
{
lblRegMessage.Text = "This email has already been registered with us.";
}
else
{
lblRegMessage.Text = "You were registered successfully.";
txtUserId.Text=(String)UserID.Value;
}
The table as well as the stored procedure is far too complex,I have simplified it for better understanding of problem.UserId is Alphanumeric.Dont worry about that.
Putting a break point shows a null against var UserID
Where am i going wrong?

Answer 1

You need to Use .ToString() on UserID
txtUserId.Text= UserID.Value.ToString();
EDIT:
var UserID = cmd.Parameters.AddWithValue("#UserId", SqlDbType.NVarChar,50);