Does the error message say what “it” is?
I suggest that you open a terminal and type
rpm --install /path/to/somefile.rpm
, and then post the output here.
It could be that you're trying to install a program without being root; this would cause a permissions problem. Try running
su -c 'rpm --install /path/to/somefile.rpm'
as well (you will need to enter your root password when prompted).