Replacement Path Variable

Dear Experts,

I have a requirement to create a report that displays 2 key figures, Created and Completed InfoObjects, based on yesterday's date. The report should be automatic and for this reason I created a customer exit (VARX) for the Created InfoObject which gets the appropriate date. Then, I am trying to create a replacement path variable to reference the value of VARX, however, the variable is not available for selection

Is this the correct implementation of such a scenario? if so any tips on how I should proceed? or should I create another customer exit and assign it to the Completed InfoObject?

Regards,

Ahmed