fSQLException when switching DB

code:

$db1 =new fDatabase('mssql', 'admin', $config->mssql->user, $config->mssql->password, $config->mssql->host);
$db2 =new fDatabase('mssql', 'account', $config->mssql->user, $config->mssql->password, $config->mssql->host);

$result= $db1->query("SELECT * from admin_users where username='benstone'");
$adminUserId= $result->fetchScalar();

$result= $db2->query("SELECT user_no from USER_PROFILE where user_id='benstone'");
$accountId = $result->fetchScalar();

$result= $db1->query("SELECT * from admin_users where username='benstone'");
$adminUserId= $result->fetchScalar();

error message:

Uncaught fSQLException
----------------------
{doc_root}\\testmultidb.php(14): fDatabase->query('SELECT * from a...')
{doc_root}\\include\\lib\\flourish\\fDatabase.php(2530): fDatabase->run('SELECT * from a...', 'fResult')
{doc_root}\\include\\lib\\flourish\\fDatabase.php(2565): fDatabase->performQuery('SELECT * from a...', Object(fResult), Array)
{doc_root}\\include\\lib\\flourish\\fDatabase.php(2195): fDatabase->checkForError(Object(fResult), NULL)
{doc_root}\\include\\lib\\flourish\\fDatabase.php(403)
MSSQL error ({null}) in SELECT * from admin_users where username='benstone'

Notes:

• When i'm trying to utilize $db1 only, it works fine.
  
• When i'm trying to utilize $db1 then $db2, it works fine.
  
• When i'm trying to utilize $db1, then $db2, then back to $db1, it always gives me an sql exception. this is also the case when i'm using fActiveRecord.
  

Hope someone can help me. Thanks!