[TYPO3-english] Frontend editing error

[Sergio Catalá Gil]

Hi list, 

when I try to add a content element in the frontend, I get the next
message:

Fatal error: Call to undefined method tslib_fe::hscAndCharConv()
in /var/www/wwwp.iti.upv.es/typo3_src-4.2.1/t3lib/class.t3lib_tceforms.php on line 4759

I was recommended to use the next patch to fix it:

http://typo3.org/teams/security/security-bulletins/typo3-sa-2009-002/

but it didn't solved my problem :-(

Any ideas? 

I'm using TYPO3 4.2.1 and tinymce_rte 0.3.3.