Device definitions disappears

I have used the feature "Device definitions" to create a definition for e.g. Galaxy s3.
Then i based an AVD on this definition.

However:
Every time i close the avd manager it seems that the definition gets deleted.
If i display details on my AVD it says "device xxx does not exist".
Is this a bug or am i doing something wrong here?

Not familiar with this issue. Note that AVD manager is part of Android SDK.