what I am going to do with my I-485 case

My case priority date is March/2005. I did inquiry yesterday. An got email like below.
Our service records indicate your application is currently pending. The processing of your application is dependent upon the category and priority date of the approved I-140 petition, as well as visa availability. At this time, there is no visa available. When there is a visa available, your application will be processed

There are must something wrong. The current visa bulletin is 4/1/2005. What I should do?