Hi,
So I think I had a similar if not the same issue as yours. I wanted to have multiple servers under a DirectAdmin server group, and my server group will be tied to an actual package in Blesta.
When adding a Service manually via Admin panel I'm given an option to select a server.
The IP of one of the servers gets saved in the Product, but it should be read from the module not the product. If I select a different server than one from the package it fails with the error you get as well.
a:3:{s:5:"error";s:1:"1";s:4:"text";s:21:"Cannot Create Account";s:7:"details";s:40:"That IP does not exist in your list<br>
";}
So I've made a fix in the direct_admin.php module that uses the IP from the module by fetching it via API from DA itself. It's a one liner placed at 1006th line in the direct_admin.php file:
$params['ip'] = reset($this->getDirectAdminIps($row));
This now solves the issue for me, so I can select the server when adding a service.
Please note that I assume that each DA node/server has only one IP, since my code gets only the first IP from the array.
I had a longer discussion on Discord if you are interested to look into more details.
Hopefully this helps.