Help to write formula in Analyzer

Hello,

I need help with the following: I am trying to write a formula in a Query that will later be displayed in an Analyzer report and what I am looking for is that -> When the result of the formula is 0, the report must show X, an error or something similar, we cannot put any number. Query Designer in SAP BW 7.5 does not allow characters to be typed, it only allows predefined elements to be dragged. Any suggestion? Thanks.

The formula is: ( 'FIELD_X' )==0 * NDIV((-1)) + (NOT ( FIELD_X)==0)) * FIELD_X)

-1 is beacuse we thought to show -1 when the result was 0, but we need character or error.