If I have this:

DECLARE @NoClient Int

SET @NoClient=3831141

SELECT TOP 1 Invoice.AddUser,Invoice.NoFormat
 FROM Invoice (NOLOCK)
 WHERE Invoice.NoClient=@NoClient AND
  (Invoice.NoStatus=5 OR Invoice.NoStatus=6 OR Invoice.NoStatus=7 OR Invoice.NoStatus=10)
 ORDER BY Invoice.AddDate DESC

This provides an adequate execution plan with simply one item at 100% exactly to the index I have created.

But, if I have this:

DECLARE @NoClient Int
DECLARE @NoStatus Int
DECLARE @NoStatus2 Int
DECLARE @NoStatus3 Int
DECLARE @NoStatus4 Int

SET @NoClient=3831141
SET @NoStatus=5
SET @NoStatus2=6
SET @NoStatus3=7
SET @NoStatus4=10

SELECT TOP 1 Invoice.AddUser,Invoice.NoFormat
 FROM Invoice (NOLOCK)
 WHERE Invoice.NoClient=@NoClient AND
  (Invoice.NoStatus=@NoStatus OR Invoice.NoStatus=@NoStatus2 OR Invoice.NoStatus=@NoStatus3 OR Invoice.NoStatus=@NoStatus4)
 ORDER BY Invoice.AddDate DESC

The execution goes completely weird simply because I passed a parameter.

Anyone can explain why the execution plan is showing a very complex plan simply because I pass my values as parameters?