SSRS - Given Key Not Present in the Dictionary

Hello Everyone,

I have just  copied a bunch of ssrs reports from live to test in order to make sure they will run within 12.5.  I am receiving this Given Key Not Present in the Dictionary error on quite a few of them.  The one I am looking  at now runs fine in BIDS and within the report manager, but from within Tessitura receiving the Given Key not Present error.  Help is appreciated, thank you!

Sheila