Hi,
Is there any error message displayed after you click 'Register'?
If you get the error code 41, please refer to the following steps to register the device.

1. Open vbox and right click on all **_Base mouse to delete -> delete all files:

2. Open the menu in the upper left corner of the vbox -> Manage Virtual Media Management, delete the files inside (as shown below), if you can't delete it, delete the similar drop-down arrow: 29a2d98c-4da0-4e86-8e4e-768cc7f81b61.vdi, any other Don't care if you report an error, just be sure. (If virtual media management is empty then skip this step)

3. Then open the vboxsever folder in the eNSP installation directory, find the five folders below and delete.

4. Open eNSP, do not add any analog devices, just click "Menu - Tools - Register Device", check all devices and re-register.
I hope this helps