I can´t read the data in the second time

There are cases than i can´t read the data one more time.
See the VB example below:

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dim rdoQuery as rdoResultset
dim strValue as string

set rdoQuery = connection.OpenResultset("SELECT '1' || '2' AS test", rdOpenKeyset, rdConcurReadOnly)

strValue = rdoQuery(0) ' Value is '12'
strValue = rdoQuery(0) ' ERROR HERE: Invalid user of Null

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The similar example work in the others DB (ORACLE, SQL SERVER, INFORMIX)

Is it a bug in the pgsql-odbc?

P.S. : I have a program to test it, if someone would like to use this, notify me, ok!!?