Well, not sure if you just copied sheets from another workbook to this sample book, but the tab name "curent schedule" was differently spelled in the formula... the formula had it as "curent shedule" (missing the "c" in schedule)....not to mention that "curent" is mispelled also.

The second thing I noticed is that the lookups in the current formula you show are referencing columns M and N in the Plan sheet, but I think they should be referencing L and M....

Anyways this is the formula revised in D31 of VACATION PLAN and, I think, pulling the right info:

=LOOKUP(LOOKUP(PLAN!$L$30,PLAN!$L$36:$L$42,PLAN!$M$36:$M$42),'Curent Schedule'!$B$4:$H$4,'Curent Schedule'!B15:H15)