Description
You have generated a type 3 instance using the Instance Wizard. In doing so you have probably copied all the dynamics of the button to a user object and assigned it the name of the button instead of using the button generated by the wizard. This is why is an "OnErrorExecute" generated when you open an image in RT or when you click the user object.

Remedy
Rename the button before you assign the name of the button to the user object.