'upgrade' returns 'install seems impossible'.

Hello,

I installed cpan in my home directory. Platform is Linux.
I start it via 'sudo cpan' and try 'upgrade' but got following errors :

cpan[3]> upgrade
..
Running install for module 'Socket'
The most recent version "1.94" of the module "Socket"
is part of the perl-5.13.11 distribution. To install that, you need to run
    force install Socket   --or--
    install F/FL/FLORA/perl-5.13.11.tar.gz
Running make test
    Can't test without successful make
Running make install
    Make had returned bad status, install seems impossible
..
Same message is repeated for many (all ?) modules.


Thanks for clarification and help.
Bye,
Bruno