Note: There is NO autosave.
1. Are you logged-in? Just click the "login" link in the Dialog box and log-in then try to save again.
2. If you only click on the Disk icon on the Left side, you will NOT save. Click on the disk icon and wait for the submenu to appear. Slide your cursor to the right and click on Save. A dialog box will appear called: Saving the project. A blue bar should move from left to right showing the Saving progress.
[ Remember to give an appropriate name for your project in the top left corner where it says: My project-page1. Click anywhere outside this Project Name area for your new project name to replace My project].
3. There may be a network connection issue at school/home. Just try to save again in a few minutes.