Don't understand how the "Get endorsed by your clients.." works!

[mahmud-rippy]

I tried to communicate with my best clients. The result is -
- Most of the clients do not response. 
- Clients who responded don't have a LinkedIn account (as I see, without client’s LinkedIn I can’t submit the form)
- Clients who have LinkedIn account say they did not receive any email from upwork, so they are unable to write me a testimonial.

I feel I need to give up it now because I see the same condition with my other two teammates who have been facing these difficulties.

[kochubei_valeria]

Hi Mahmud,

Sorry to hear you haven't been able to use the Testimonial feature yet. It is correct that a client has to have a LinkedIn profile in order to be able to write a testimonial for  you. They should receive an email though, so it's strange they haven't. Could you please click on my name next to this post and send me more information and links to profiles of clients who didn't get emails about your requests?