71 911 T tachometer won't work with MSD 6AL Ignition
 

All,
Have a 71 911 T that I replaced the old Mark 10 Bee with a MSD 6AL, cannot get
tach to work, also have MSD #8910 tach adapter, red wire for tach adapter
is 12V off the coil & white wire from tach adapter splices into white wire from MSD 6AL to distributor. Purple and black wire from tach ties into white wire before the splice? tried MSD tech support, no help, not sure about wiring or transistor. any help would be greatly appreciated. :confused:

Thanks,

Jens