AVG Won't Scan on Mac

I installed it a few days ago, it ran once and did some background protection, but now I can't get it to scan manually.

Hello Adrienne,
We regret for the inconvenience caused.
Could you please confirm whether you have installed AVG Antivirus for Mac first time in your pc? or you have already installed in your pc? so that we are happy to assist you better.
Feel free to contact us for any further assistance. Thank you.

I downloaded the free Mac version of AVG Antivirus. However, when I try to scan, it says, "Unable to start scan! (Failed to send the command.)" How can I get it to scan?

Adrienne, For your info, just in case that you are unaware, you can post the screenshot (http://avgclick.me/getscreenshot) here in your topic. Click on 'Answer' & then click on the 'Image' [mountain symbol] & follow the instructions. Also there would appear to be an issue with Mac OS & scanning. Have a look @ this link (https://support.avg.com/answers?id=906b0000000LR8RAAW).
AVG Guru

Hello Adrienne,
We apologize for the inconvenience caused.
Have you tried to uninstall and reinstall AVG program?
Have you received any error message while you tried to scan your system?
If possible, could you please provide us the screenshot of the error message you have received?
Thank you.

Hello Adrienne,
We regret for the inconvenience caused.
Could you please confirm whether you have installed AVG Antivirus for Mac first time in your pc? or you have already installed in your pc? so that we are happy to assist you better.
Feel free to contact us for any further assistance. Thank you.

Here's the screenshot. 

User-added image

I installed it a few days ago, it ran once and did some background protection, but now I can't get it to scan manually.