Working great for 1,2,3 & 4th occurances, but if i pass in 5 for april 2010, i am getting the wrong date

For example:

SELECT dbo.getNthOccuranceOfWeekDay(YEAR(GETDATE()), MONTH(GETDATE()), 1, 5)

Resulting in:

2010-04-18 00:00:00.000

Should be:

2010-04-25 00:00:00.000 (because the 25th is the last occurance of sunday in April.

Please advise.

Edit: my above issue occurs with Mitesh Oswal's version only, the version from Rajneesh Kumardev does not suffer from this problem.