Unfortunately I wasn't here earlier to see the topic, but maybe late answer can also help.
The problem cristian320 described is caused by loss of contact from one of decoder's two outputs: if you connect only one output and the ground, decoder rotation will "push" buttons paired to decoder at BBI card alternately. The output wires should be checked - something is not connected well. (From my experience: the problem is always with the last connection that you check...)
It is also important to be very careful with detecting which of three pins at the decoder is common one (this one should be connected to BBI's ground pin; it is not always the middle one) - if it is mixed, the result is also strange.
Edit: Oh, yes, of course, BBI's inputs has to be paired for decoder through bbi-config utility, the card doesn't recognise decoder automatically.
With this preconditions, LINDA works wery well with BBIs and decoders.