Currency on modifier list is different from functional currency

Hi

We are using LCM Service and we have set up formulas on Advanced Pricing module as a modifier list. We want to set up the currency on the modifier list as foreign (i.e. not the functional currency). However, this is not generating the charges. On the contrary, when we set up the currency on the modifier list as the functional currency, then charges are generated.

Can anyone tell me is this is standard functionality or can we use foreign currency on modifier list?

Rgds

Zaynah