Most Common text result in a selection If certain value present

Here's my sheet showing the data I'm trying to collect on a separate front table

Screen Shot 2015-06-18 at 5.51.08 PM.png

I'm trying to display the most common "Ad Source" for all calls placed to "Clinic Location" "ME"

Here's my formula
=IF(('PCC Call Data'!J3:J246,(INDEX('PCC Call Data'!B3:B246,MODE(IF(('PCC Call Data'!B3:B246<>"")*ISNA(MATCH('PCC Call Data'!B3:B246,$Z$466:$Z466,0)),MATCH('PCC Call Data'!B3:B246,'PCC Call Data'!B3:B246,0)))))),"")

I placed the "IF" statement at the front of the "INDEX" statement but I'm not getting a positive result. the INDEX statement functions well on its own, grabbing the most common result, but I can't expand it to include the IF statement for each different locations.

I'm looking for location-specific results for our inbound marketing campaigns.

Appreciate any help I can get.
Thanks!
Alex