Hello TiFa LoCkHeArT
It would appear to be the card then but can I ask whether the card has ever worked in the card reader on the computer running Windows 8 and is the Windows 8 installation a recent upgrade.
Check if the drivers for the card reader are installed, you can use DriverView
If the drivers are installed open the Folder Options in the Control Panel, select Appearance and Personalization and then Folder Options .
Select the View tab in Folder Options and then clear the Hide empty drives in the Computer folder check box/circle and click OK, let us know how it goes.
To add to the adapter information from Wolfey can I ask if the adapter has a tab on the side of it to write protect the data on the card, if yes is it in the correct position.
You are welcome BTW