[TYPO3] ipVars problem

[Nikola Galanov]

Hello all,

I wrote a little plug in that lists my database table and searches 
inside it. The problem is that it works only if I'm logged in as admin 
in the BE. Otherwise

if(isset($this->piVars['search_button']))
     ...
     ...
     ...

doesn't work.

I have typo3 4.0.2.

Do you know this problem? Or there is a wrong configuration on my server?

Please help me
Nikola