Forum OpenACS Development: Error raised when trying to test the queries

After porting the data-model, I am now up to porting the queries in
the xml files in the tcl directory.
One of the queries I have ported is as follows:

<!--FIX ME PLSQL
FIX ME PLSQL

begin
      :1 := cal_item__new(
        on_which_calendar  => :on_which_calendar,
        activity_id        => :activity_id,
        timespan_id        => :timespan_id,
        creation_user      => :creation_user,
        creation_ip        => :creation_ip
      );

end;
-->

select cal_item__new (
                null,
                :on_which_calendar,
                null,
                null,
                :timespan_id,
                :activity_id,                                null,
                'cal_item',
                null,
                now(),
                :creation_user,
                :creation_ip
)

I put the my query into psql to see if it works or not and I received
the follow error

ERROR:  Cannot insert a duplicate key into unique index acs_objects_pk

Does anyone know how to fix that?

This is what I put into psql (I just made the data up for testing
only):

select cal_item__new (
            8,
            1,
            null,
            null,
            2,
            3,
            null,
            'cal_item',
            null,
            '07/01/1996 10:30:00',
            4,
            'me'
)