unlink doesn't work

I am trying to use unlink command on my server Apache/2.2.3 PHP Version 5.2.10. I have been using the same script on a bunch of other servers including my local PC. Unfortunately, the command doesn't work.

I tried this so far:

• chmod everything to 777
• puttin开发者_运维问答g new files and unlinking them
• also I notice that I can't upload or saveXML files to the server

I am guessing that it is some kind of setting inside the php.ini file, but I don't know which.

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May be it's a safe_mode?

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Solved

Checking if it is writable first and then unlink it seem to do the trick

if (is_writable("$bannerlink")) unlink("$bannerlink");

thanks to everybody