stored procedure

hi

below procedure is for update  or insert.but  everytime it inserts  new  row  with previous row data and updated one   not updating  existing row.

ALTER PROCEDURE [dbo].[sp_WorkStatus]
	-- Add the parameters for the stored procedure here
	@ID int,
      @WalktestStatus  nvarchar(50)
      ,@WalktestComments nvarchar (max)
      ,@InstallationStatus   nvarchar(50)
      ,@InstallationComments  nvarchar (max)
      ,@ppSatus  nvarchar(50)
      ,@ppComments nvarchar (max)
AS
BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from
	-- interfering with SELECT statements.
	SET NOCOUNT ON;

    -- Insert statements for procedure here
	
if exists (select * from WorkStatus where ID=@ID and WalktestStatus=@WalktestStatus and  InstallationStatus=@InstallationStatus  and  ppSatus=@ppSatus)

begin 
update  WorkStatus set WalktestStatus=@WalktestStatus,WalktestComments=@WalktestComments,InstallationStatus=@InstallationStatus,InstallationComments=@InstallationComments,ppSatus=@ppSatus,ppComments=@ppComments where ID=@ID and  WalktestStatus=@WalktestStatus and InstallationStatus=@InstallationStatus and  ppSatus=@ppSatus
end
else
BEGIN
	insert into WorkStatus(ID,WalktestStatus,WalktestComments,InstallationStatus,InstallationComments,ppSatus,ppComments) values (@ID,@WalktestStatus,@WalktestComments,@InstallationStatus,@InstallationComments,@ppSatus,@ppComments)
End
end

output:

 ID       walkteststatus  walktestcomm     instastatus     instacomm        postprocsta     ppcoments
1	8	In Process	in progress	In Process	in progress	In Process	in preogress
2	8	Complete	Completed	In Process	in progress	In Process	in preogress
3	8	Complete	Completed	 Complete	not compled	In Process	in preogress
4	8	Complete	Completed	 Complete	not compled	On Hold	its on hold not working
5	8	Complete	not complet	 Complete 		Complete  	its completed
6	8	On Hold	Completed	 Complete		Complete  	its completed