I can not update by using ''check for updates'' but i can by ''Do it now''

Comodo Internet Security - CIS AntiVirus Help - CIS
#1

Hi every body
I can not update by using ‘‘check for updates’’ but i can by ‘‘Do it now’’ option on the left hand. When i click on ‘‘check for updates’’ and start it, gives me this alert:‘Checking for updates…An error occurred while updating.’
please help me fixing this problem.

#2

What version of CIS are you using?

#3

Also, Make sure you run Diagnostics
(CIS > Help Icon (Top Right) > Support > Diagnostics)

Thanks…Jake