First of all you have to do indexing from
and select all the option and select “Reindex” from the right side of the page and press “Submit” button.
and after that, just change the name of 4 files which are following.
1). app/code/local/Zver/Slider/Block/Adminhtml/Slider/edit.php to Edit.php
2). app/code/local/Zver/Slider/Block/Adminhtml/Slider/grid.php to Grid.php
3). app/code/local/Zver/Slider/Block/Adminhtml/Slider/Edit/form.php to Form.php
4). app/code/local/Zver/Slider/Block/Adminhtml/Slider/Edit/Tab/form.php to Form.php