PLL bode plot in ADE XL by means of ams simulator

Hello,

I implemented  a Analog PLL in Virtuoso. Each model (Phasedetector , Low Pass Filter, VCO) is modelled by means of a Verilog AMS Code. The models are then connected with each other in a schematic (compare figure attachement).  Generelly speaking I am amble to simulate the PLL in ADE XL by means of the ams simulator. The results are as expected. But when I tried to simulate the bode plot of the PLL I just got a straight line for the transfer function |H(jw)| eventhough I should expect a low pass characteristic.

Can anyone tell me how I can obtain the correct bode plot for the transferfunction of the APLL ?

Looking forward to your replys. Thanks heaps