I have a working Slony-I setup with one master and one slave.  I tried to run a simple alter table add column statement via execute script.  This always worked for me, however today it failed.

I got this error (truncated) on the slave:

2014-12-05 21:51:14 SAST ERROR  remoteWorkerThread_1_1: error at end of COPY IN: ERROR:  schema "_appcluster" does not exist
CONTEXT:  SQL statement "select _AppCluster.sequenceSetValue($1,$2,NULL,$3,true); "
COPY sl_log_1, line 1: "1       4065328 \N      13346355        \N      \N      S       \N      {"alter table future_details add note_adm text;"..."
2014-12-05 21:51:14 SAST ERROR  remoteWorkerThread_1_1: failed SYNC's log selection query was 'COPY ( select log_origin, log_txid, NULL::integer, log_actionseq, NULL::text, NUL
L::text, log_cmdtype, NULL::integer, log_cmdargs from "_AppCluster".sl_log_script where log_origin = 1 and log_txid >= "pg_catalog".txid_snapshot_xmax('4065328:4065330:406532
8') and log_txid < '4065334' and "pg_catalog".txid_visible_in_snapshot(log_txid, '4065334:4065334:') union all select log_origin, log_txid, NULL::integer, log_actionseq, NULL::
...

Why am I getting this error that the schema does not exist?  If I insert data into a replicated table on the master, it appears correctly on the slave.  

On the slave:

oasis=# \dn
    List of schemas
    Name      |  Owner   
---------------+----------
_AppCluster | postgres
public        | postgres
(2 rows)

Can anyone provide advise?

Thanks
Waldo