Admin page is blank

[TehForum]

I have installed vBulletin, but when I go on the Admin CP page, it's just white and blank. I'm using 3.8.6 version, I have re-installed it twice but still the same problem

[Brandon Sheley]

<a href="http://www.vbulletin.com/docs/html/blank_pages" target="_blank">Here are the known causes of blank or 'white' pages:</a>

[TehForum]

I'm still having problems after doing that