Hi Victor,
What version of the SellFire theme do you have installed? If it not the latest, please try downloading the new one and installing. Also, what version of WordPress are you using?
I just tried the latest plugin with Tweaker4, your theme, and things seem to be functioning normally.
Also, the quickest way to get support is to submit a message via the SellFire.com website or to email [email protected]
Thanks,
Jason