Measure to count a value from different tables with differing date relationships (pls read)

techies - thanks but it's not working. I can't see the wood for the trees at the moment. I think, really, I may need someone to re-write my opening DAX, which takes the dates from Power Query parameters, to use the dates from the date dimension in the slicer visual. I'm too confused at present to even breakdown the need. I need to step away from it.