Adding multiple google adsense code to webpage

I'm having trouble adding multiple adsense blocks to web pages. At first I thought that we weren't allowed to do this, but I see many website with adsense blocks on both sides of the pages and in the middle. I believe we are allowed to have 3 per page, if I read the rules correctly. Well, when I place in the code for 2 of these placeholders, only one shows up in the preview. What is happening here? I'll try exporting and uploading the the website and see if it works there. Any help would be much appreciated. thx

I believe I found the answer from previous threads. I swear i searched and searched, but they said that I have to upload to server before it will work.

I got it figured out. I'm getting better at this.]