I wonder why I can't choose the following configuration option against tuners ?

1. Tuner A - Positioner
2. Tuner B - second cable of motorised tuner A
3. Tuner C - third cable of motorised tuner A (element not available yet)
4. Tuner D - fourth cable of motorised tuner A (element not available yet)

With the following configuration VuDuo2 is using 2 tuners A + B only:

1. Tuner A - Positioner
   
2. Tuner B - second cable of motorised tuner A
3. Tuner C - simple (Hotbird)
4. Tuner D - simple (Hotbird)

Tuner C and D aren't available - signal strength is 0 !

The only working configuration I found is:

1. Tuner A - Positioner
   
2. Tuner B - simple (Hotbird)
3. Tuner C - simple (Hotbird)
4. Tuner D - simple (Hotbird)
   
   

Does anybody could advice how to handle properly my configuration ?
I would like to have possibility to use my motorized dish with all 4 available converters (and tuners) on any satellite I choose.