VerticalResponse accounts created through the VerticalResponse website are incompatible with VR for AppExchange (there are exceptions for older VerticalResponse accounts). When you click the VR Email tab within Salesforce a new VerticalResponse account will be created using the email address on your Salesforce account.
If you have an existing, incompatible VerticalResponse account with this email address then you will need to change the email address on your existing VerticalResponse account for Salesforce to create a new, compatible account. Click the Account tab in your VerticalResponse account to change your email address.
Please contact our support team if you need help changing the email address on your existing VR account.