Displaying Messages Dependent On Format?

I'm trying to create a more user friendly (and easily updated) gantt chart for marketing campaigns running throughout the year. The difficulty is that we have approximately 100 products and each product can have anything up to 20 campaigns per year (never overlap, though, fortunately).

Campaign data is on one row per product in columns B:CC (each campaign consists of start date, end date, name and volume) but these are hidden from the user. The conditionally formatted chart runs from CD2:QD108 and is predominantly based on the start and end dates.

When any coloured cell is selected I want the relevant campaign name to be displayed, like a data validation message.