Sitecom N300 and Billion BIPAC 7800N setup problem

Hi all, I want to extend my wifi network (Billion BIPAC 7800N), friend gave me Sitcom N300 wireless range extender he did not need, and all would be good, but one problem.
On Bipac, I use MAC filtering for extra security, while setting up the Sitcom I switched MAC filtering off, and set extender in Universal Repeater Mode, and set up password and everything was working. I added Sitcom extenders MAC address to MAC filtering option on Bipac, but when turn MAC filtering on, I can't access internet if connecting to extender. If I switch MAC filtering off, everything is fine.
Is there anything else I need to fix in my router options? or MAC filtering won't work with extender at all?
thanks