Trying to make Asset/CI Managed by APM

Products

• CA IT Asset Manager
• CA Software Asset Manager (CA SAM)
• ASSET PORTFOLIO MGMT- SERVER
• CA Service Management - Asset Portfolio Management
• CA Service Management - Service Desk Manager

Issue/Introduction

I am trying to check the Managed by CA APM box on an asset. When I check the box I get a message:
Warning: The Asset could be a Configuration Item from CA SDM. Assign Model to this asset before saving it.

If I try to add a model I get an error:
You cannot change the Asset Family for an existing asset.

Environment

Release:
Component: ARGIS

Resolution

When you open the asset in APM, check the asset family and class. Also subclass if there is one. 
Choose a model that has the same asset family and class and save.