...you didn’t click yes when the JAVA Security certificate popped up Please take the time to read each window message and select yes and continue. This may take some time to load, so please be patient.
...you do not have Java enabled.
Go to your my WebCT page and click on the 'Check Browser' link.
Scroll down. If there is a green check next to an item related to Java, then you know the problem is not Java related.
..you are not using the correct browser.
If you are using a Mac, please click here.