applying reaction force operator on an inner boundary

Hello,

I'm trying to calculate normal mass and heat flux on an inner geometry boundary (no boundary condition is applied on the boundary) using the reacf() oprator (reacf(p) for mass and reacf(T) for heat), but I get zero, though It shouldn't be zero. How can I perform an exact integration?

Under the integration settings section, in method-> summation is set of course.
The store reaction forces check box in the output section in the solver’s Settings is checked.
(I'm using version 4.3)

Regards,
Roi