Address not occupied by a tag - TIA

Software version: TIA Portal V13 SP1 Update 5

PLC: S7-1515

Currently monitoring two Double words within seperate DB's to trigger an an output. On compilation I get the error "The address is not occupied by a tag"

The code works, and downloads fine. My OCD isn't liking the fact I've got errors though. Is there another way of doing this that won't cause the error?

(Please ignore the glaring spelling error haha)