Help needed for weired B2 RFE

My parents applied B2 extention a couple of month ago and got a RFE last week. There are 4 materials required in total. One of them is very weired.

"Please documentary evidence that you have the ability to financially maintain yourself throughout the duration of your stay.
An affidavit of support is insufficient evidence of an ability to financially maintain yourself"

I don't understand why "An affidavit of support is insufficient". However, since my parents both retired and obviously their salary in China couldn't support their stay here.

What evidence I can use? Any suggestions? Thank you very much.

所有跟帖： 

• Provide your bank statments for the past few months. -mytwocents- ♂ (95 bytes) () 09/18/2006 postreply 06:56:28

• Thanks, mytwocents.Any other thouths out there? -del_pe- ♂ (332 bytes) () 09/18/2006 postreply 07:21:43

• Have you included an I-134 with the application. -mytwocents- ♂ (197 bytes) () 09/18/2006 postreply 07:37:35

• No. we didn't. But it clearly says "affidavit of support", which -del_pe- ♂ (490 bytes) () 09/18/2006 postreply 08:05:40

• The officer, I think, does not want only to see a I-134 -mytwocents- ♂ (302 bytes) () 09/18/2006 postreply 08:17:42