1. Enable debugmode in gsconfig file.
2. Make sure that PHP has write permission in "data/imanager/" folder
3. Go to 'ItemManager' Tab > 'Categories' and remove: 'imforms_cache', 'imforms'
4. Delete the file config.php under /plugins/im_forms/inc/ directory, if exists.
5. Try the installation again
P.S Make sure there are no JavaScript errors in your browser's console during installation.
2. Make sure that PHP has write permission in "data/imanager/" folder
3. Go to 'ItemManager' Tab > 'Categories' and remove: 'imforms_cache', 'imforms'
4. Delete the file config.php under /plugins/im_forms/inc/ directory, if exists.
5. Try the installation again
P.S Make sure there are no JavaScript errors in your browser's console during installation.