Why listeners don't work when I use a NI PCI 6229 ?!

I made a GUI that opens a Simulink model and get data from the simulation using listeners. It works well when I use a source block from the Simulink library, such as the Sine Wave block. Now I've tried to use a Simulink model with the block that gets the signals from the NI PCI 6229 board. The problem is that, when I run my GUI and the simulation, the listeners don't even work. The signals are fine, I can see them with the Scope block. Does anyone know what I can do?!