I'm updating the question as I solved one of the problem in this question. The original question is below the line.
I'm now able to see the preview of the image as the problem was with the below code
$fieldset->addField('banner', 'image', array( 'label' => Mage::helper('designer')->__('Banner'), 'required' => false, 'name' => 'banner', ));
where instead of
file was written for the type of field. But now the problem is, I'm unable to delete the previous image. I do check the
delete image checkbox but the file still remains there. Why its not deleting?
I'd created a module with module creator and able to save images. But when the next time I do want to edit the record it does not show the preview of the uploaded image or the delete checkbox.
Do I need to write additional code in my adminhtml tab form?