Error in COALESCE Stored Proc

Dear All

I have the following stored Proc:-

ALTER PROCEDURE dbo.HS_Players_GetPlayers_BY_Criteria
(
@HamTeamsIDint,
@Namenvarchar(100),
@Surname nvarchar(256),
@PosIDint,
@PageIndexint,
@PageSizeint
)
AS
SET NOCOUNT ON

IF @HamTeamsID = 0SET @HamTeamsID = NULL
IF @Name = '0' SET @Name = NULL
IF @Surname = '0' SET @Surname = NULL
IF @PosID = 0SET @PosID = NULL


SELECT * FROM
(
SELECT HS_Players.playerSurname, HS_Players.playerName, HS_Players.fk_hamTeamID, HS_HamTeams.hamTeamName AS HamTeamName, HS_Players.fk_posID,
HS_PlayerPos.positionName AS PositionName, HS_Players.playerDOB, HS_Players.playerEmail, HS_Players.playerPrevClubs, HS_Players.playerProfile,
HS_Players.playerIntApp, HS_Players.playerActive, HS_Players.playerCareer, HS_Players.AddedBy,
ROW_NUMBER() OVER (ORDER BY playerSurname DESC) AS RowNum
FROM HS_Players INNER JOIN
HS_HamTeams ON HS_Players.fk_hamTeamID = HS_HamTeams.hamTeamID INNER JOIN
HS_PlayerPos ON HS_Players.fk_posID = HS_PlayerPos.playerPosID
WHERE (HS_Players.fk_hamTeamID = COALESCE (HS_Players.fk_hamTeamID, @HamTeamsID))
AND (HS_Players.playerName = COALESCE (HS_Players.playerName, @Name))
AND (HS_Players.playerSurname = COALESCE (HS_Players.playerSurname, @Surname))
AND (HS_Players.fk_hamTeamID = COALESCE (HS_Players.fk_hamTeamID, @HamTeamsID))
--WHERE (HS_Players.fk_hamTeamID = COALESCE (HS_Players.fk_hamTeamID, ''))
--AND (HS_Players.playerName = COALESCE (HS_Players.playerName, ''))
--AND (HS_Players.playerSurname = COALESCE (HS_Players.playerSurname, ''))
--AND (HS_Players.fk_posID = COALESCE (HS_Players.fk_PosID, ''))
) HS_Players
WHERE HS_Players.RowNum BETWEEN (@PageIndex*@PageSize+1) AND ((@PageIndex+1)*@PageSize)
ORDER BY HS_Players.playerSurname ASC

This stored proc is always returning all the values, no matter what parameters I pass to it.

Can you guys tell me if I have any errors in the COALESCE statements since I am not an expert in SQL Server yet.

Thanks

Johann