How to solve a warning "thc_pin_masqued"

Hi all,

I have a simple design in DEHDL using an old component that has a hidden ground pin (no supply, it's an octal transistor with a common ground). The message is:

WARNING (thc_pin_masqued)
                Implicit PowerPins on instance
                Instance : i170(1)
                GND

I've checked that the ground pin has been allocated to the correct signal, can anyone tell me what causes this message?

best regards

George