Dynamic Name ranges and data validation problems

Please see sheet attached...bit hard to explain

BUT on the sheet "commission paid", ive given dynamic name ranges to the sales rep people (by Month, so NR "Jan" has column A, NR "Feb has column I, etc) using the offset function, which is working fine.

BUT on the RS working sheet, I have used a data validation based on another data validation.

So, Column D, is where i want to select a month, jan or feb for example, and then in Column A, i want the relevant names to appear from the named ranges.

It WAS working fine, before i started using the dynamic name ranges, I used it as i wanted to get rid of the blank cells that occur if i just select the list data of names....

....Please help me!