changing port in NIMAX for a Network connected device

Hi all 

I am having a Keithely 2460 which is connected via ethernet cable and is having a fixed IP. In NIMAX, under Netwowrk device i am able to see the device. But under settings, when i try to change the port number, i am getting the following error message. ( see attached image) 

" There was a problem saving the settings for the device, Could not access the resource". 

But i can access the device and  use the web user interface via the IP Address. 

And if i click "Open Visa Test panel", i get the error: "Error opening resource: VISA: ( Hex 0xBFFF0011) insufficient location information or the device or resource is not present in the system" 

Anyone have any idea about this problem. 

I am having NIMAX 19.5.0f0

Thanks in advance