utl_http packages gives undefined exception

I use the statement : select utl_http.request('http://www.oracle.com') from dual

and it gives me error:

ORA-06510: PL/SQL: unhandled user-defined exception
ORA-06512: at "SYS.UTL_HTTP", line 152
ORA-06512: at line 1

Any ideas what could be the cause? I'm logged in as system. Using 805 standard edition.

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Terry Dykstra
Canadian Forest Oil Ltd.