How do I write a member formula BS & IS prior year data for trending?

Summary:

Trying to create a member formula to use for balance sheet trending in PBCS.

Content (required):

I am trying to write a member formula that will do the following calculation in each of the remaining forecast months:

(prior year accrued expenses/prior year OPEX)

But I am not sure where to begin. Our balance sheet data is in a different POV from the income statement, e.g.:

BS =No_Department, No_Location, etc.

IS= Total Departments, Total Locations, etc.

Below was the last formula I tried, but it didn't seem to work. The end goal is to have a trend % that can be used to forecast balance sheet items out.