No button visible – Plugin short code manager

After downloading and activating the plugin ‘short code manager’, there should be a new icon in the menu bar when you adjust/add a new page. Actually there is no button visible!

Does someone knows this problem? I also tried to instal and activate another type of plugin: ‘ Easy short code manager’ but the button for this plugin is also missing in the bar..

I’ve downloaded a nice theme, but for this theme I really need to use the ‘ short code plugin’ as the designer integrated some specific options for the layout within this function.

Please let me know, thanks in advance,

With kind regards!