Problem Batch converting AI to PNG files

I have several hundred small AI files that I need to convert to PNG files.  I know this can be done in the AI batch converter, but I am having a different problem using that route.  What I want to should be possible in PS, so I am trying this route, too.

I have used the PS batch converter many times, but I still think its sorcery.  Sometimes I get it to work, and sometimes not. 

What I typically do is have the original artwork (AI files in this case) in one folder, and I save the PNG files into a separate file.  Doing this manually is no problem, but I have 400+ files this round and I would like to batch process them.  I created a batch action of the following steps:

Open File (opening AI file in PS)

Convert file from CMYK to RBG

Save As PNG

Close file

I set the batch to Source "Override Action Open Commands" and Destination "Override Action Save As commands" (this set of toggles usually works for me).

When I run the batch it correctly generates the first new PNG file in the correct destination folder.  However when it works on all further files in the source folder, it overwrites the first file in the destination folder.  For example, if I have 4 source files:

A.ai

B.ai

C.ai

D.ai

I end up with a single file in the destination folder "A.png", but the artwork is from "D.ai".   I have tried tinkering with different settings in the batch processor with no luck.  At this point I am baffled.  This is probably something stupid simple but I am not seeing it.

thanks,

Tom