Credential Errors

Hi

What i'm trying to do is get the OE_OrderUI.asp page to popout from a customer record within CRM by creating a button for it in advanced customisation.

Here are the results i get on the server

https://youtu.be/7yte_noAZe0

Here are the results i get on client machine (non domain admin - even with domain admin on a client machine / same error-issue)

https://youtu.be/If3zaMtiBdU

Is this something simple I've overlooked?