Rx + p106

Hi. I just bought a cheap rig of 5 p106 cards, but I want to split some cards to my non-full rx rigs. Tried to mix one p106 with 2 rx running xmr-stak, and I can;t manage to get it to work. xmr-stak (indeedminers) don;t seem to recognize my rx, but they are present. It only mine with the p106. Any idea of a specific configuration argument I may have missed? Thank you