Getting Error While Insertion

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go


ALTER PROCEDURE [dbo].[usp_World_Ins_data]
-- Add the parameters for the stored procedure here
@UserName nvarchar(50),
@Password nvarchar(15),
@Email nvarchar(100),
@IsChecked bit,
@ReceiveNews bit

AS


BEGIN

SET NOCOUNT ON;

IF EXISTS(SELECT UserName FROM World_Registration WHERE UserName=@UserName)
RAISERROR('Username exists',16,1)
ELSE IF EXISTS(SELECT Email FROM World_Registration WHERE Email=@Email)
RAISERROR('Email exists',16,1)
ELSE
INSERT INTO World_Registration(UserName,Password,Email,IsChecked,ReceiveNews)
VALUES(@UserName,@Password,@Email,@IsChecked,@ReceiveNews)

END


if executed once it works properly like
[usp_World_Ins_data] 'aa','aa','ravinderpal@netbiz.in','1','1'

while if i m trying to execute stored procedure like this three times
i mean more than one time
[usp_World_Ins_data] 'aa','aa','ravinderpal@netbiz.in','1','1'
[usp_World_Ins_data] 'aa','aa','ravinderpal@netbiz.in','1','1'
[usp_World_Ins_data] 'aa','aa','ravinderpal@netbiz.in','1','1'

it gives error:
Msg 170, Level 15, State 1, Line 2
Line 2: Incorrect syntax near 'usp_World_Ins_data'.

pls help me