Salesforce, Creator of Agreement Unable to Send for Signature (Hosted)

I have inherited a Salesforce and Adobe Echosign implementation. We are trying to use the host signature option as we would like the client to sign using one of our salesmen's iPads having first created the Agreement as normal within Salesforce. The logged in user can create an agreement, but when they try to Send the the agreement for signature (i.e. generate the document on screen to sign it)  we get the following message

"You are currently logged in as Logged in User Name. In order to view your document, please logout of this account."

If we log in as a different user, navigate to the Account and Agreement a different user can then Send the document ok.

So, this seems like it's a permission issue but we can't find an EchoSign configuration option to restrict it in this way. It's as though there is a rule which say the Account owner, cannot host a signature, but an alternative user can?