BUG #4322: Problems with field not updatable

The following bug has been logged online:

Bug reference:      4322
Logged by:          Alexandre Caneo
Email address:      alexandre@adtinformatica.com.br
PostgreSQL version: 8.2.6
Operating system:   WIN XP
Description:        Problems with field not updatable
Details:

I'm using Win XP SP2, VB6 and PostgreSql 8.2.6.

When I select the datas with this instruction
"select a.x from a,b where a.z = b.z order by 1"
the program run very well and I can insert, update and delete rows. But,
when I select any column from table b an error occurs when I try to modify
the column value from textbox for an example.
"Binding Collection Error. field not updatable".

String connection
    ls_StrConn = "PROVIDER=MSDASQL.1; DRIVER={PostgreSQL UNICODE};
DATABASE=" & ls_Conexao & "; SERVER=" & ls_Host & "; PORT=" & ls_Servico &
"; UID=" & ls_login & "; PWD=" & ls_Senha & "; ByteaAsLongVarBinary=1;"

Recordset's properties
  mo_Record.CursorType = adOpenDynamic
  mo_Record.LockType = adLockOptimistic

  mo_Record.Open mo_Command

One more thing.
I don't need update the table's b column, just show them.

Any suggestions would be appreciated.
Best regards.
Alexandre.