This is in continuation with the post : Get a Skype Button on your WordPress blog
Solution : Check the “Allow my status to be shown on the web” settings which is shown under privacy tab in Skype.
Here is how you do it,
1. Open Skype program.
2. Select Tools -> Options on Windows or select Preferences on Mac.
3. Select Privacy Settings.
4. Click the “Show Advanced Options” button. (only for Mac)
5. Finally tick on the “Allow my status to be shown on the web” check button.
6. Click “Save” in the Options dialog to exit.
And now it should work ! :)