lookupvalue with date variable

[Jebilaya]

I am trying a (what I thought would be simple) lookupvalue Dax which is to take use the period start date from the table below minus 7 days and look it up in my date table

Unfortunately it returns a blank value.  If I use the period start date the lookupvalue formula works fine so it's something to do with the -7 days.  It's definitely returning the -7 days as a date / time format.

Any ideas?

[TomasAndersson · Accepted solution]

Weird, I can't replicate your issue. Works when I just set up a date table and a "fact table" with an opening date.

Do you have a relationship between your opening date column and master date table? Does the master date table have a large enough date range to give a result for all lastweekdates? 

Maybe if you can share more data or a sample file it can be easier to see what happens.

[Jebilaya]

It was the relationship piece @TomasAndersson 

Thanks