Variable names in Universe

Hello,

I am creating universes based in BEx queries. Most of the times everything works fine, but there is a strange behaviour with variables' names that I don't understand: there are variables that maintain the same name that they have in BEx query, but there are other variables (almost all of them) which are renamed to something like 'V0000XX'.

Is there anyone that knows why this happens?

Thanks in advance.

Eva Duarte