error installing xenforo

Hello everyone,

I have just bought xenforo to replace a current vbulletin installation.
This morning I was beginning the installation of xenforo, and immediately after entering the database properties ,after clicking "test & generate configuration" I get this errormessage:

Fatal error: Call to undefined function mysqli_set_charset() in /home/klusforum/domains/ on line 337
I was suspecting that mysqli was not installed, but after asking to my hostingprovider they told me it is installed...

Does anybody have any idea, or does anybody can give me a hint how to continue..

Kind regards,

Yes, everything is fine now. Next step is to import users/forums/content from current vBulletin forum. But first i take some time to take a look into the management interface, and implement a dutch translation.

Thanks for helping!