Hello Tariq,
This message can appear for various reasons. It may be due to a poor internet connection. It could also be due to network restrictions that block the use of a VPN.
For example, some users in UAE are not able to access SecureLine using Etisalat. There are other examples with local networks (inside a company or school network).
Without more info it's difficult to say what the cause might be.
Please open a support ticket and include your log file there:
https://www.avast.com/supportThe log file can be found by going to C: drive, then program data, avast software, avast, log. It is called secureline.txt
Best regards,
Davidek