Table JX 1.5.7 installation error on Joomla 1.5.15

Hi.
I've bought, downloaded and installed Table JX 1.5.7 on my Joomla 1.5.15.
Unexpectedly the Grid component (while creating a new grid) shows a lot of error messages: a list of notices at the top of the panel and two notices in the connection grid.
Hope to hear from you soon for solving the problems.

Here are the errors:

Notice: Trying to get property of non-object in .\administrator\components\com_grid\models\grid.php on line 360
Notice: Trying to get property of non-object in .\administrator\components\com_grid\models\grid.php on line 361
Notice: Trying to get property of non-object in .\administrator\components\com_grid\models\grid.php on line 362
Notice: Trying to get property of non-object in .\administrator\components\com_grid\models\grid.php on line 363
Notice: Undefined offset: 1 in .\administrator\components\com_grid\models\grid.php on line 372
Notice: Undefined property: stdClass::$default_order in .\administrator\components\com_grid\models\grid.php on line 390
Notice: Undefined offset: 1 in .\administrator\components\com_grid\models\grid.php on line 392
Notice: Undefined property: stdClass::$secOrder in .\administrator\components\com_grid\models\grid.php on line 395
Notice: Undefined offset: 2 in .\administrator\components\com_grid\models\grid.php on line 396
Notice: Undefined offset: 1 in .\administrator\components\com_grid\models\grid.php on line 397
Notice: Undefined property: stdClass::$filter in .\administrator\components\com_grid\models\grid.php on line 401
Notice: Undefined offset: 1 in .\administrator\components\com_grid\models\grid.php on line 403
Notice: Undefined property: stdClass::$connection in .\administrator\components\com_grid\models\grid.php on line 122
Notice: Undefined variable: _DB in .\administrator\components\com_grid\models\grid.php on line 143
Notice: Undefined variable: _DB in .\administrator\components\com_grid\models\grid.php on line 147
Notice: Undefined variable: _DB in .\administrator\components\com_grid\models\grid.php on line 147
Notice: Undefined property: stdClass::$tableName in .\administrator\components\com_grid\models\grid.php on line 162
Notice: Undefined property: stdClass::$connection in .\administrator\components\com_grid\models\grid.php on line 163
Notice: Undefined property: stdClass::$idGrid in .\administrator\components\com_grid\views\grid\view.html.php on line 33

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in connection:

Notice: Undefined property: stdClass::$connection in .\administrator\components\com_grid\views\grid\tmpl\editform.php on line 102
checked onclick="enableConn()"/> Same as Joomla's

Notice: Undefined property: stdClass::$connection in .\administrator\components\com_grid\views\grid\tmpl\editform.php on line 104
onclick="enableConn()"/> Other