help I-485: what is this for? thx

I just got this message requesting more information for my I-485 application, what is this for? Thank you very much for your reply.

**********************************

Application Type: I485 , Application to Register Permanent Residence or to Adjust Status

Current Status:

On October 26, 2005, we mailed a notice requesting additional evidence or information in this case. The notice explains in detail what additional material is needed. If you have questions about the notice, what is required, or if 14 days have passed and you have not received the notice, please call the National Customer Service Center at [phone].