Some error notice

I like the plugin although I have just started trying it. But unfortunately there is some errors appearing. I’m using wp 3.5.1

I’ve got these errors notice on page Manage Downloads.

Notice: Undefined index: mode in /public_html/wp-content/plugins/wp-downloadmanager/download-manager.php on line 29

Notice: Undefined index: id in /public_html/wp-content/plugins/wp-downloadmanager/download-manager.php on line 30

Notice: Undefined index: filepage in/public_html/wp-content/plugins/wp-downloadmanager/download-manager.php on line 33

Notice: Undefined index: by in /public_html/wp-content/plugins/wp-downloadmanager/download-manager.php on line 34

Notice: Undefined index: order in /public_html/wp-content/plugins/wp-downloadmanager/download-manager.php on line 36

Notice: Undefined index: perpage in /public_html/wp-content/plugins/wp-downloadmanager/download-manager.php on line 38

Notice: Undefined index: search in /public_html/wp-content/plugins/wp-downloadmanager/download-manager.php on line 40

And these error notices when I tried to open a file with the Nice Permalink download links and a 404 page:

Notice: Trying to get property of non-object in /public_html/wp-content/themes/meraminus-d-02/functions.php on line 29

Notice: Trying to get property of non-object in /public_html/wp-content/themes/meraminus-d-02/functions.php on line 29

Notice: Trying to get property of non-object in /public_html/wp-content/themes/meraminus-d-02/functions.php on line 29

Notice: Trying to get property of non-object in /public_html/wp-content/themes/meraminus-d-02/functions.php on line 29

Notice: Trying to get property of non-object in /public_html/wp-content/themes/meraminus-d-02/functions.php on line 29

Notice: Trying to get property of non-object in /public_html/wp-content/themes/meraminus-d-02/functions.php on line 29

https://www.ads-software.com/extend/plugins/wp-downloadmanager/