I was working with a 2600 when we could only get one rx to accept. It would lock out the other 2 on the cart, after sitting with stellar support for two hours at 11 pm, and getting nothing outta them other than it was the rx, we went into the cart setting and found that the runs were all placed on zero, this happens after a software update, the way I took it. Under the cart set up we needed to specify how many runs were going to each tower. (in this case 5) after this was set all the rxs read and we were on the way.