Reports & Discoverer :: Pick Latest Record Rank And Count?

Am working on a workbook to count the number of enrolments and withdrawals in the program. My data looks like this

name semester status year
A 1 enrol 2010
A 2 withdraw 2010
A 3 enrol 2010
B 1 enrol 2010
B 2 withdraw 2010

I want to count their latest status only. It should come up with
Total Enrol - 2
Total Withdrawn - 1

For total Withdrawn, I tried 'rank' and filter to equals 1 but it does not allow me. Is there any way to have this work?
Here's my calculation:(decode((FIRST_VALUE(status) OVER(PARTITION BY year, name ORDER BY semester DESC)),'withdraw', name)) It tells me that 'Aggregation of Analytic function not allowed'