Tax indicator 0 is not defined for use with condition type ZNAV

Hi gurus

I person been requested to make immoderate information tables for taxation determination successful the instauration of POs, I person created them, assigned them to an entree series and delegate this to the customized information benignant ZNAV. This information benignant has information people D (taxes), calculation benignant B (fixed amount) and information class D (tax). 

One of the information tables is built with the fields "Destination country" and "Tax classification material", and erstwhile I'm trying to make caller records successful mek1, erstwhile I effort to participate the worth 0 successful "tax classification material"  this mistake comes up: "Tax indicator 0 is not defined for usage with information benignant ZNAV" (it besides happens for different values)

Does anyone knows what I americium missing?

Thanks,

Álvaro