转身份F2-F1,谁遇到过这种情况?

kissfireUID: 2137488

之前一直是case received and pending. 今天收到email状态更新，

Current Status: Undeliverable Document Filed.
On July 8, 2009, the post office returned the document we mailed to you as
undeliverable. Please call 1-800-375-5283 to update your mailing address, so
we may re-send the document to you.

很奇怪的是，
1. 地址就没动过，之前还收到他们reciept的notice.
2.不管是要求补材料或者什么，之前一点更新也没有，现在突然说 Undeliverable
Document Filed.

那位大侠给分析一下，多谢了！自认为材料都交的很齐了.