Hi,
I have created the following formula but it's not working and I'm wondering if someone out there can tell me where I've gone wrong:

=SUMIFS((VLOOKUP((CONCATENATE(A151,E151)),(CONCATENATE(Timesheets!D$1:D$6000,B$1:B$6000))),MAX(Timesheets!E$1:E$6000),Timesheets!AV$1:AV$6000)

So what I'm essentially trying to do it have this formula combine info from 2 columns on one sheet and 2 columns on another sheet in the same workbook. If those columns have the same info then I'm looking for the maxiumum value in a 3rd column to narrow down the rows applicable to be added up. Once it has determined that information it is to add the applicable rows in yet another column on the second sheet to return my result. I don't know if that even makes sense the way I've explained it but I am totally confused and getting a little frustrated at this point.

Any help would be GREATLY appreciated!