No "Taxi to Gate" options - Help?

Hi all,

I have been flying a few rounds of "Free Flight" using a Boeing 747-400, landing in several major airports (i.e. Los Angeles Int'l, Heathrow, Hong Kong Int'l (New)).

Everytime I touchdown on the runway, I was not given the option to contact ground, until the tower advised me to get off the runway when possible.

When contact is established with ground, I usually find myself with only 2 options - Taxi to Takeoff, or Taxi to Parking/ Fueling. When I select Taxi to Parking, I am always directed to park in general aviation.

What is it that I am not doing (or doing wrong), which results in me being denied options to Taxi to Gate?

I have checked everytime, and there were plenty of gates for Heavy available in the airport. My traffic density is set at 40%.

Help/ Advise is appreciated.

Thanks!