VMImage "not found" error when adding second role

When I trying to add a second role to a deployment with the REST API, I am getting the error:

<Error xmlns="http://schemas.microsoft.com/windowsazure" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"><Code>ResourceNotFound</Code><Message>VMImage vnscubed3502-ul-x8664-azure-5QgR not found.</Message></Error>

When I use the api to get the list of images, the output in includes:

<OSImage>
    <Category>User</Category>
    <Label>vnscubed3502-ul-x8664-azure-5QgR</Label>
    <Location>East US</Location>
    <LogicalSizeInGB>10</LogicalSizeInGB>
    <MediaLink>http://cohesiveft.blob.core.windows.net/vhds/vnscubed3502-ul-x8664-azure-5QgR</MediaLink>
    <Name>vnscubed3502-ul-x8664-azure-5QgR</Name>
    <OS>Linux</OS>
    <IsPremium>false</IsPremium>
    <OSState>Generalized</OSState>
</OSImage>

My XML for the add role includes:

     <VMImageName>vnscubed3502-ul-x8664-azure-5QgR</VMImageName>
     <MediaLocation>http://cohesiveft.blob.core.windows.net/vhds</MediaLocation>

Are <VMImageName> or <MediaLocation> incorrect or is there some other field related to the image that is also required ?  Any help would be greatly appreciated.

    Thanks,