What could be RFE on I-140

[sunny_1010us]

Hi,

After 400 days of filing my I-140 I just checked status online and it said they send RFE on my case.

What could be the RFE on I-140?

Thanks
Sunny

 

[zz2006]

It could be ability to pay, education requirments, problems with past experience letters, etc...good luck!