Can't select remote agent for Avamar server during discovery

Hi

I'm using DPA 6.3 for this first time.  I have the app server, datastore server and an agent set up, and have successfully tested and added  one agent and one Data Domain system. I'm now trying to add an Avamar server. I'm running the Discover Wizard. In step 4 Data Collection Agent, I see two choices:

Local Data Collection Agent installed on the host

[bold] It is not recommended to use a local ageng on the Avamar server

Remote Data Collection Agent installed on another host

Following the recommendation, I want to use the Remote Data Collection. But I can not select the radio button next to this option, and the 'Select Data Collection Agent' option is greyed out.

When I use the DPA GUI and select Admin -> System -> DPA Collection Agents, and look at my one agent, it shows that it is enabled and seems to be good-to-go.

What would be causing this behavior?

Thanks

tl