Issue with Keyboard

Hi

I have a logitech wireless keyboard. When using it up until recently I have been able to press the cmd button and then click on the emails I wish to delete in one go. They all change colour and I can then press the delete key and they all disapear.

For some reason , and only in EM Client this function has stopped working. It is taking me ages to remove unwanted email from my inbox. CAn anyone help me. I am using a Macbook air with a Logitech MX wireless keybard.

Many thanks in advance.