accessing other users via database links

We're having trouble with executing a procedure via a database link. The procedure is not stored directly in the user that the link points to, but another user on the same instance.

More accurately:

There are two databases (=instances), DB1 and DB2. DB1 has user A.
DB2 has users B and C.

Sqlplus on user C:
  create or replace procedure brb as
  ...
  grant execute on brb to B with grant option;

Sqlplus on user A:

  create database link B_link connect to B   identified by .... using 't:mashine.xxx.no:DB2';

  exec C.brb_at_B_link;

The exec seemed to work when there was no parameters to brb and when brb did not contain any commit.

With parameters and commit I get

ORA-02088: distributed database option(?) is not installed
ORA-02063: before line from DB1
ORA-02054: the transaction 1.4.99142 is doubtfull
ORA-06512: at "C.BRB", line 3
ORA-06512: at line 1

...this also seems to lock any tables that are updated in the brb procedure. Any helpful tips or suggestions on this matter will be appreasiated.

--
Kjetil Skotheim