AMPscript Sales Cloud Task Creation

I'm trying to create a Sales Cloud task using AMPscript. There's not much detailed documentation out there so I'm trying different API field names and haven't figured it out. Here's my code:

    var @createtask    set @createtask = CreateSalesforceObject('Task', 6,'Priority', 'High','Status', 'Not Started','OwnerId', 'xxxx','WhoId', @ID,'WhatId', 'xxxxx','Subject', 'Task 123'        )