ALN Domanis in parameters

Sgrisket

I have a BIRT report with 3 parameters; for 2 of them I would like users to choose among a fixed list of values.
In BIRT I can set them as combobox, but Maximo doesn't accept it, so I thought I could do it using ALN Domains, but I still haven't been able to.
Can somebody help me?
Thank you.