Simulink universal bridge IGBT with PWM

Hi

I am using an Universal Bridge Block from the SimPowerSystems library. It is set up as an IGBT/Diodes with 3 bridge arms, and I want to control this block with a PWM signal.

First I used a PWM generator (2 level) block, also from the SimPowerSystems lib. and everything seems to work fine. But I had a task of making a PWM model myself, slightly modified in terms of the carrier wave. The build in model uses a saw tooth waveform from -1 to 1, and my model is using a saw tooth waveform from 0 to 3. Well, I managed to build this PWM block, and the output is matching the output from the build in block exactly, so it seems to be working.

Here is my confusion. When i connect the output from my own PWM block and measure the voltage on the IGBT converter, i get zero on all lines!!? This does not happen when I use the build in block, even though the output signals are exactly the same as with my block?

Does anybody have any suggestions to what is going wrong here?