[TYPO3-english] t3blog problem with comments

[Patrik]

When I add a comment on the post I get a white screen (when is enable power
error log get an error: "Fatal error: Call to undefined function:
array_diff_key ()" ).
I use a antispam-function (ext. sfpantispam).
On the server has PHP 4.3.9 .

Regards,
Patrik