Cannot activate Drobo Apps but get Update-Message

Hi all,
we have two 5N2 running with DroboDR between the two. For one Drobo (the DR target) I get daily reminders in Drobo-Dashboard that ther are app updates.
BUT: Apps are not activated on that Drobo and I cannot activate the apps, because in the admin settings the box for app activation is greyed out.
Any ideas?