Errors upgrading to 1.2.2.1

[artflow]

Hi,

I've tried to upgrade my prestashop installation for two days now, but I cannot get it to work. I try to follow all instructions exactly, but after the upgrade i get this when trying to access the frontend:

Fatal error: Declaration of SEKeywords::getData() must be compatible with that of ModuleGraph::getData() in /Users/mats/Sites/prestashop/modules/sekeywords/sekeywords.php on line 13

The back-end isn't accessible at all, and I cannot log in (I get a bunch of error messages). Can anyone help please. I've tried to upgrade on a MAMP-server as well as online on my service-provider's machines.

-mats