Software Management Solution Agent not installing on new computers

I am running 7.1 SP2 MP1. Package delivery works fine on older clients, but on new machines it is not working. Other tasks such as scripts work fine. I have enabled the following:

Agents/Plug-ins -> Software -> Software Management -> Software Management Solution Plug-in Install

Agents/Plug-ins -> Software -> Software Management -> Software Management Solution Plug-in Upgrade

Now the new computers are getting "Software Delivery Results Pickup Agent", version 7.1.7858, but not "Software Management Solution Agent", which shows as 7.1.7580 on the older machines. Am I enabling the wrong policy? Also, what does this "results pickup agent" actually do?

Thanks,

ZC