Admin user cannot checkout a workflow

[HugoFirst]

I have a workflow which has been published and I need to change it.

So I open it up, I can see the workflow and I see the gear icon.

I click the gear icon and I see the following options:

New Workflow

Open Existing

Copy

Delete

Set Inactive

Expand Transitions

Validate Workflow

Properties

Edit Stages

Edit Catalog Variables

Notice that there is no option to "Checkout".

Other information:

1. The workflow in question shows "Published" in the header line.

2. The admin user can open other workflows and see the option to Checkout.

3. The build tag for our instance is glide-eureka-04-08-2014__patch10-03-25-2015

Why is this happening?   And more importantly, how can I change the workflow?

[EdwinRandall]

You may have an instance setup with Domain seperation, in this case when you impersonate you need to change to the domain for the user you impersonate for.