[support] problems installing modules

Hi all. so, I have the new drupal update, which is 7.27 and the way I use to install modules is I use to goto my modules area in my admin panel on drupal and click the install modules link, then I would go to either upload a module or enter URL, in which case I have tried both. well, when I click install, nothing happens it just takes me back to the previous screen! and when and if I try to click the install button for the second time, it just brings up a black screen. in short, it doesn't even take me to the ftp settings for installing the modules any more... does anyone knows why this is happening? Thanks.