In what order are the cards inserted in your A4000? I had the same problem with an A4091 and X-surf (first version). I wanted to have the A4091 in the top slot of the A4000D and stick an extra harddrive on it, but for some weird reason it refused to boot when a zorro2 board was before it on the zorro bus, so I moved it to slot no. 2, above my P-IV, and inserted the Delfina and Xsurf above it (after it on the bus), and everything works fine.
Try this.... it might work.
-Paul