TINA/Spice/LM2576: LM2576 doesn't work properly on OrCAD Pspice

Tool/software: TINA-TI or Spice Models

Hi,

I'm trying to simulate the LM2576 Pspice Transient Model from http://www.ti.com/product/LM2576/toolssoftware but the model is not working properly. Using OrCAD Pspice is mandatory.

This is my schematic:

For example, if I simulate the ouput I don't get a constant duty cycle

Another example is the inductor current, it should be a triangular waveform but I get this

And this is how it should works (from webench)

I would appreciate your help, than you!