not work third ports/Xem module of Acceleport XEM

not work third ports/Xem module of Acceleport XEM
I am experiencing problems with installing a third Digi PORTS/16em Module. The COM ports in third modulate Digi PORTS/16em Module do not work(COM port 37 to 52), whereas the port in modules 1 and 2 passes the test(com port 5 to 36).
The third I modulate has the adapter mark digi of 7,5 VDC and 800mA Part Not: 1001202A

Other Information:
My current drivers for Digi AccelePort Xem PCI is 7.0.15.0
PCI /Xem 1MB S/N:60321265, P/N:5000493 REV:G
Module PORT/16EM P/N 50001078-02

When you add a third Ports module to a chain, you’ll need to also use an Auxillary Power Supply on the third module. The first two modules in the chain will be drawing power from the Host Adapter card. Also, make sure the EBI cable going to the third module is plugged into EBI In.