Hi Mikhail,
Thank you for your response.
The KEPServerEx which I’m using it provides OPC DA.
Here is its link: https://www.kepware.com/en-us/products/kepserverex/
By the way, I’ve tried to fix the error by following your links, but this error still happened.
Please let me know if you have any further clue for this case.
Your sincerely,
NITI