[EpiData-list] How to calculate in epidataanalysis

To the list: I do have a database with the fields weight (floating number) and height (floating number). I can make operations like defining a new floating variable and using the command newvariable = height/2 or newvariable = height*height but when I tri to define IMC ## and then IMC=weight/(height^2) or IMC=weight/(height*height) I do receive a "data tipe mismatch" as an answer. I cant have an answer when I try to get age as agemonths=(visitdate-birthdate)/30 The same calculations work with epiinfo for dos with the same datafile. Gerson Zanetta de Lima Brazil