Asp.net Page Is Unable To Retrieve The Right Data Calling The Store Procedure From The Dataset/data Adapter

I'm trying to figure this out

 I have a store procedure that return the userId if a user exists in my table, return 0 otherwise

------------------------------------------------------------------------

 Create Procedure spUpdatePasswordByUserId

@userName varchar(20),

@password varchar(20)

AS

Begin

Declare @userId int

Select @userId = (Select userId from userInfo Where userName = @userName and password = @password)

if (@userId > 0)

return @userId

else

return 0

------------------------------------------------------------------

I create a function called UpdatePasswordByUserId in my dataset with the above stored procedure that returns a scalar value. When I preview the data from the table adapter in my dataset, it spits out the right value.

But when I call this UpdatepasswordByUserId from an asp.net page, it returns null/blank/0

 passport.UserInfoTableAdapters oUserInfo = new UserInfoTableAdapters();

Response.Write("userId: " + oUserInfo.UpdatePasswordByUserId(txtUserName.text, txtPassword.text) );

 Do you guys have any idea why?