two queries on the same object (Help)

Hi,..
My name is Yuan,..
I am new to Pear

I get this error code :
MESSAGE: You cannot do two queries on the same object (copy it before
finding)
TYPE: PEAR
DEBUG INFO:
CODE: -1


What does it mean?

Where to go to find meaning of error code lika this ?



Thanks



YUAN

Ps. I use  Pear on Seagull Frame work and

here is a piece of code i am trying to do :

// Generate select box of Client specific to entity
$oClient = & new DataObjects_Client();
if($output->isJSO != 1) $oRateType->whereAdd("entity_id =
$iEntityID");
$oClient->orderBy('organization_name');
$result = $oClient->find();
if ($result > 0) {
$aClient = array();
while ($oClient->fetch()) {
$aClient[ $oClient->client_id ] =
$oClient->organization_name;
}
}
$output->Client = SGL_Output::generateSelect($aClient);