Reply to a post - no permission

Hi:
relatively new here. I have run into an issue a few times. I see a post and want to reply. But I get a "do not have permission" notice pop up.

Example below and the notice I get. ??
I am logged in, I can search, I can post new threads, but some posts I cannot reply to.

?
William

Are you using a VPN when this happens?

I usually do use a VPN. I turned it off. I had to log in again. Found the post I want to reply to and...nope, will not let me.

I noticed that this post/thread has an option below it for a "Quick Reply" with a Message box in it. The post I want to Reply to only has the blue box icon with a checkbox and "POST REPLY" in it that does not let me post. This message DOES allow me to click the "POST REPLY" and brings up Reply box. I am posting this in the "Quick Reply" message box.

If you are trying to reply to an ad, you need to send them a PM. You can't reply on the post itself. Click on their name and in the drop down pick send message. Or, is that were you see the red message box, in the send message drop down?

If you look at the first image in initial post - on lower left - it shows I may post new threads, replies, attachments, and edit my posts. The red message box appears after I click "Post Reply"...

Click on his username and send a message from the dropdown menu. Sorry I haven't used the classifieds for a while and had a brain fart.