**HELP** Error call functions!!

When I try to add a page, i get this error on my blog. The same when I try to delete it. Oddly, the page gets created and deleted but this error is there. Can someone help me with this please?

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, ‘createRewriteRules’ was given in /home/nipples/public_html/wp-includes/plugin.php on line 414

Warning: Cannot modify header information – headers already sent by (output started at /home/nipples/public_html/wp-includes/plugin.php:414) in /home/nipples/public_html/wp-includes/pluggable.php on line 865