I need help with a formula that will give me a ranking but does not have gaps in the numbers. The ranking is based on a couple criteria like what date and department they are in.

example
Name Dept Points Ranking Should Look like
Carol Ops 4 1 1
Tanya Ops 5 2 2
Nicole Ops 11 3 3
Frank Ops 11 3 3
Dianna Ops 13 5 4
Robyn Ops 15 6 5
Stu Exp 4 1 1
Lindsey Exp 8 2 2

This is the formula I have but it gives gaps
=SUMPRODUCT(([Department]=[@Department])*([Class]=[@Class])*([Week Of:]=[@[Week Of:]])*([Weekly Total Rank Points]<[@[Weekly Total Rank Points]]))+1