Thanks for joining this thread, PaceSvcs, 

The AVG antivirus software is maybe blocking QuickBooks. That's why you're unable to send invoices with one of your company.

You'll want to make sure QuickBooks has the right permissions. You can either manually change your system permissions or modify your antivirus software settings.

Change your system permissions

1. You can edit your INI system file to give QuickBooks the right permissions.
2. Open QuickBooks Desktop.
3. Press F2. Then press F3 to open the Tech Help window.
4. Go to the Open File tab.
5. Find and select QBW.ini from the list. Then select Open File. This will open the file in Notepad.
6. In Notepad, add a new line at the bottom of the text. Add [QBWEBMAIL]CUSTOM_CERT_ENABLE=1 to the line.
7. Go to File and select Save. Then close Notepad.
8. Close and restart QuickBooks.

You can also lookup specific steps for how to set up permissions in your antivirus program for how to set up permissions.

After that, open QuickBooks and resend invoices to customers. If the same issue persists, I recommend chatting with our QuickBooks Desktop Team. They can further investigate what's causing this one company not to send entries.

Here's how to contact them:

1. Go to Help, then select QuickBooks Desktop Help.
2. Select Contact Us.
3. Enter your concern, then select Continue.
4. Choose Start messaging to connect with a support expert.

Let me know how this goes by clicking the Reply button below. I'm always around whenever you have follow-up questions.