VPN Certificate Unable To Import Error

Greetings to all, I am here in the hope that someone may help me out with a solution for this error.
I have a network setup, where I have a few clients installed and all my clients are giving this error when I try to send some data through them.
It gives some, certificate import failure error as you can see in the images given below.
Error 39: Unable to import certificate.
May be, you have faced this error and know how to resolve it. That’s why I have posted this question here.
I need an expert’s opinion to resolve this issue, as this error is appearing on all my clients and none of the clients are working properly. So I hope that if there is a VPN Expert out there, then I must receive a solution based reply soon.
