ER error :Could not read from received stream

HI, Madison, Folks, ISD10 UC5 AIX 5.3 What is the possible reason for the following error? ER servers have been successfully started and connected between two sties. Interesting is that update can be replicated from site1 to site2, but NOT vice-versa(see between). Thanks, Frank informix@dora $ more ris.osdint2_grp.ncdcint_grp.D_2.070416_20:06:37.1 TXH Source ID:6 / Name:ncdcint_grp / CommitTime:07-04-16 20:06:36 TXH Target ID:5 / Name:osdint2_grp / ReceiveTime:07-04-16 20:06:37 ---------- RRH Row:1 / Replicate Id: 327681 / Table: noaa@informix.abc_test / DbOp:Insert RRH CDR:45 (Error: Could not read from received stream.) / SQL:0 / ISAM:0 RRD 1304|?|? ========== TXH Transaction aborted TXH ATS file:/tmp/RepErr/ats.osdint2_grp.ncdcint_grp.D_2.070416_20:06:37.2has also been created for this transac tion informix@dora $ more ats.osdint2_grp.ncdcint_grp.D_2.070416_20:06:37.2 TXH RIS file:/tmp/RepErr/ris.osdint2_grp.ncdcint_grp.D_2.070416_20:06:37.1has also been created for this transac tion ========== TXH Source ID:6 / Name:ncdcint_grp / CommitTime:07-04-16 20:06:36 TXH Target ID:5 / Name:osdint2_grp / ReceiveTime:07-04-16 20:06:37 TXH Number of rows processed when transaction was aborted:1 TXH One or more rows in a transaction defined with tx scope were rejected TXH CDR:45 (Error: Could not read from received stream.) / SQL:0 / ISAM:0 ---------- RRH Row:1 / Replicate Id: 327681 / Table: noaa@informix.abc_test / DbOp:Insert