The field contents in Dbgrid do not appear

In a dbgrid, I want to display some fields of the accounts payable table and the field vlparcela_parcelasapagar of the parcels to pay table ..

So I made a join in both tables ...

See the example

Select P.* ,
C.fan_clifor, 
PP.vlparcela_parcelasapagar,
from 
contasapagar p,
parcelasapagar pp, 
cli_for c, cademp e
where p.cdconta_contasapagar = pp.cdconta_contasapagar
and P.cod_clifor = c.cod_clifor
and P.cod_emp = e.cod_emp
and C.tipo_clifor = 'F'

After I save using the POST method of clientDataset and Commit, the value of the field portion of vlparcela_parcelasapagar in dbgrid does not appear.

I have to close the accounts payable screen, reopen it, then show the value ...

How do I at the moment I save it shows the value of field installments to pay .. ???

To show on the grid I'm using ClientDataset ...

When I save, after using the POST command, I put a refresh and also put like this: cds.close; cds.open (I opened and closed) but it did not work ...

How could I do ?? Is there a solution in this case?

I'm using Delphi 2010, dbexpress and firebird 2.0