Any idea why LTC3813 (boost smps) simulation is not working?

Hello,
Any ideas much appreciated.
The LTC3813 appears to be turning off and on. ITH pin going up and down.
Do you know why?
LTspice sim attached

ok, sorted now, ITH misconnection.

With the LTC3813, do you know what is the purpose of the PLL pin? I appreciate its synchronisation, but many pwm controller ic's do sync without having a PLL pin. Does the PLL pin mean that if multiple LTC3813's have their sync pins connected together, then they will all switch at the fastest frequency, whatever that may be?
The only other chip i've seen a PLL pin with is another linear.com chip where the PLL was involved in interleaving. There is no interleaving with the LTC3813 so do you know what the PLL pin is for?

Some applications require the switching frequency to be synchronized to a reference clock frequency. One reason for that is so that any EMI from the switcher is at a known frequency, to keep it away from sensitive system frequencies. I ran into such a requirement on a NASA satellite system.