close_session() fails with socket errors.

Attempting to close a session using close_session('session_id') has no effect, and shows socket errors in the vertica log. interrupt_statement('session_id', statement_id) also has no effect. Log looks like this: 2013-09-10 11:12:47.170 Init Session:0x2b9d3c50bd40-c0000000a7d2fc [Session] [Query] TX:c0000000a7d2fc(xxxx03-9520:0x29c3da) select close_session('xxxx03-9520:0x26a581'); 2013-09-10 11:12:47.255 Init Session:0x2b9d3c50bd40-c0000000a7d2fc [Session] session xxxx03-9520:0x26a581 socket shutdown error: Transport endpoint is not connected Any suggestions?