Moving onto next cell based on criteria

[kasperblue]

I have two sheets, one with information I want updated based upon information in the other sheet.

I have a series of 75 dates that I want updated for each row (i.e a sum of column AJ in the "orders" sheet) IF a)the date appears in the "orders" sheet AND b) the ID matches the "orders" sheet. If the date doesnt appear I want the cells it to be left alone i.e. from a previous update.

I have attached an example.

I cant seem to get the code to see if the date appears in the "orders" sheet and ONLY update if the date exisits?

Can anyone help me please?