HELP!

I've been searchign thru the database trying to find out how to pull from
one tab the largest value of an array.

I need to find the longest wait time per month per group. Originally I had

=SUMPRODUCT(--((Skill_Calc!$A$2:$A$65499)=$A46),--((Skill_Calc!$C$2:$C$65499)=$E$4),(Skill_Calc!$L$2 :$L$65499))

Where A46 is "01Month" and E4 is the group name, but I realized I am not
summing the values--I need the max.

This doesn't work. :(

=SUMPRODUCT(--((Skill_Calc!$A$2:$A$65499)=$A46),--((Skill_Calc!$C$2:$C$65499)=$E$4),MAXA(Skill_Calc! $L$2:$L$65499))