Connection refused error on starting SwitchML reference driver on Tofino Model

[sahiltyagi4]

I was able to compile the P4 program with P4Studio SDE 9.9.0 on Tofino model (not the real h/w, just the tofino model)
However, when I run driver switchd, I recurrently get the following error: connect failed. Error: Connection refused.

Any idea what could be causing this? Let me know if you need me to share any specific logs. Thanks!