NSC RFE LUD today

I just checked the case status and found my I140 application got LUD today, but the content didn't change. Does anyone have same experience and know what that mean? My case was opened to review or it's going to be denied?
I got RFE in November, and send response on Jan 27.The officer is EX001, I'm so worry about my case because my backgroud is not strong at all and NSC is really tough.
Thanks for any inputs.