Add attachments not possible

I'm install the new version (Enterprise 24.1.150 (32bit) on my company Laptop and its not possible to add attachments (*.pdf) with the mouse !?! only links are possible.
Is that a general problem ?
Is there anywhere a option for attachments ?
What could be the reason for that ?

If I open a old map (created with the old version) attachments are shown and could be open but it's not possible to attach new files.
from the MM help
The Map Index task pane Elements list displays all the topics on your map that contain attachments and links. If your system administrator has disabled the Attach Files feature, you will not see the Attach Files command on the ribbon. When you open a map that contains attached files, you will see the disabled attachment icons.
So I think it's not a problem of the admin?

The other way with the right button and "add attachment" works fine.