postgresql-8.1-413.jdbc3.jar ignoring setPrepareThreshold();

I have slight problem on a postgresql-server-8.1.11-1PGDG.rhel4 db.
The first statement below runs fine. But the second two statements
return no results. When these statement are not run as prepared
statements they work fine. I need to run them as a prepared statement
because of the parameterization, but I don't want the server to cache
the prepared nature of the statements. These statements worked fine on
an old 7.3 driver. The only differendce I could see was that the driver
didn't prepare them.

Dec 18 10:10:56 devel postgres[5404]: [2-1] LOG: duration: 362.004 ms statement: EXECUTE <unnamed> [PREPARE: select aggregationvalue.value as
Dec 18 10:10:56 devel postgres[5404]: [2-2] aggregationvalue$value,aggregationvalue.aggregatetype as aggregationvalue$aggregatetype,aggregationvalue.count as
Dec 18 10:10:56 devel postgres[5404]: [2-3] aggregationvalue$count,aggregationvalue.stoptime as aggregationvalue$stoptime,aggregationvalue.starttime as
Dec 18 10:10:56 devel postgres[5404]: [2-4] aggregationvalue$starttime from aggregationvalue where date_trunc('month', aggregationvalue.stoptime) between $1 and $2 and
Dec 18 10:10:56 devel postgres[5404]: [2-5] aggregationvalue.aggregatetype = $3 and split_part(aggregationvalue.value,':',1) = $4 and
Dec 18 10:10:56 devel postgres[5404]: [2-6] split_part(aggregationvalue.value,':',2) like $5 and split_part(aggregationvalue.value,':',3) like $6 ]

Dec 18 10:11:05 devel postgres[5404]: [4-1] LOG: duration: 31.000 ms statement: EXECUTE <unnamed> [PREPARE: select aggregationvalue.value as
Dec 18 10:11:05 devel postgres[5404]: [4-2] aggregationvalue$value,aggregationvalue.aggregatetype as aggregationvalue$aggregatetype,aggregationvalue.count as
Dec 18 10:11:05 devel postgres[5404]: [4-3] aggregationvalue$count,aggregationvalue.stoptime as aggregationvalue$stoptime,aggregationvalue.starttime as
Dec 18 10:11:05 devel postgres[5404]: [4-4] aggregationvalue$starttime from aggregationvalue where date_trunc('month', aggregationvalue.stoptime) between $1 and $2 and
Dec 18 10:11:05 devel postgres[5404]: [4-5] aggregationvalue.aggregatetype = $3 and split_part(aggregationvalue.value,':',1) = $4 and
Dec 18 10:11:05 devel postgres[5404]: [4-6] split_part(aggregationvalue.value,':',2) like $5 and split_part(aggregationvalue.value,':',3) like $6 ]

Dec 18 10:11:05 devel postgres[5404]: [6-1] LOG: duration: 2.000 ms statement: EXECUTE <unnamed> [PREPARE: select aggregationvalue.value as
Dec 18 10:11:05 devel postgres[5404]: [6-2] aggregationvalue$value,aggregationvalue.aggregatetype as aggregationvalue$aggregatetype,aggregationvalue.count as
Dec 18 10:11:05 devel postgres[5404]: [6-3] aggregationvalue$count,aggregationvalue.stoptime as aggregationvalue$stoptime,aggregationvalue.starttime as
Dec 18 10:11:05 devel postgres[5404]: [6-4] aggregationvalue$starttime from aggregationvalue where date_trunc('day', aggregationvalue.stoptime) between $1 and $2 and
Dec 18 10:11:05 devel postgres[5404]: [6-5] aggregationvalue.aggregatetype = $3 and split_part(aggregationvalue.value,':',1) = $4 and
Dec 18 10:11:05 devel postgres[5404]: [6-6] split_part(aggregationvalue.value,':',2) like $5 and split_part(aggregationvalue.value,':',3) like $6 ]

The sum of the Universe is zero.