Notebook Adaptor Problem

I have an MN-500 Base Station, MN-510 USB adaptor for
another desktop, and MN-520 notebook adaptor for an HP
notebook. All is working fine. The HP is dated so just
bought a new Dell notebook with XP to replace the HP. I
ran MSBN setup and loaded the software but it does not
recognize the MN-510. I took the 510 out and put it back
in the HP and it works fine. I tried several times to
carefully put the 510 in the Dell slot, but to no avail.
Would appreciate any advice on how to proceed.