Create form using query doesn't fill fields

Hi,
I have question, I want to create form using query. I made a form in which I
choose from one table field, and then the other fields on my form should be
filled in with appropriate row from table.
I already tried query, and it works. But, when I choose one paramether on my
form, and then press command button to refresh form data, nothing happend?
Why???
Maybe it's connected with Primary key? I have Primary key in my table, but I
think if I didn't do something good, in that case even query shouldn't work?!
But, my query works, only I have problem with filling form fields