Hi I am trying to install multisites (com_multisites_V1.2.17) on Joomla 1.5.15 - everything installs OK - however when I go to the "Check Patches" area (I have made all listed files writable) and then click "install" the page refreshes saying that patches where installed correctly with success - however when I try navigate away from the page or go to preview the site I just get a blank page with no error message - just blank. This happens in both Admin backend and front end.

I have even tried an older version of multisites to see if that helped and the same problem happened.

I then have to upload the backup files to restore joomla to a working version and have tried installing a few times now with the same thing everytime.

your help would be greatly apreciated

thanks

The most frequent reason is a PHP syntax error somewhere that could result by a blank page.
Sometime you have an error.log file that store the PHP syntax error.
Try also to see in your hosting administration tool if you have a PHP error message reported.

When you say error in back-end and front-end.
Is this on the master website also or just in a a slave site ?