If Exists Command Returning An Error

Hello, can anyone see a problem with this T-SQL? 1 set ANSI_NULLS ON
2 set QUOTED_IDENTIFIER ON
3 GO
4 ALTER PROCEDURE [dbo].[Logon_P]
5 @User_ID VARCHAR(50),
6 @User_Password VARCHAR(50)
7 AS
8
9 IF EXISTS(SELECT 1
10 FROM [User]
11 WHERE [User_Name] = @User_ID)
12 BEGIN
13 RETURN 1
14 IF ((SELECT User_Password FROM dbo.[User] WHERE [User_Name]) = @User_ID) = @User_Password
15 BEGIN
16 RETURN 2
17 END
18 END
19 ELSE
20 RETURN 0
21 Its returning the following error:Msg 4145, Level 15, State 1, Procedure Logon_P, Line 11An expression of non-boolean type specified in a context where a condition is expected, near ')'.