Go to Edit > Preferences > Advanced > Cache and click "Clear Memory Cache" and "Clear Disk Cache". Also check to see that "Document in cache is compared to document on network:" is set to "Every Time". Click OK to accept the changes, and restart Netscape before viewing your page again.

If you are using Internet Explorer:

Go to View > Internet Options (or Tools > Internet Options for IE5), and look on the General tab under "Temporary Internet Files". Click "Delete files". Next, click the "Settings" button, and make sure that "check for newer versions of stored documents" is set to "Every visit to the page". Click Apply, then restart IE before viewing your page again.