Can I distribute existing campaign activities to new members of a marketing list in CRM 2011?

I have a campaign with some campaign activities. They are connected to a dynamic marketing list. Once every week I want to update the marketing list and distribute the campaign activities to the new members of the the marketing list. But I can't, because the "Distribute campaign activities" is disabled. It is only enabled the first time I distribute a campaign activity. Is this function by the design in MS CRM 2011? Are the any changes in newer versions?

Regards,

John Martin