include() for URL is not working!

Hi! I'm using one machine and would like to include file from another machine using the php code. I saw some articles mentioning about include("url") and I tried that but I got an error saying that it could not find the file. Machine #1 --> It's url address is https://www.test.net PHP code --> include("https://www.test.com/test.php"); Machine #2 --> have file called test.php Since I got the error message, so I checked out the website on the 2nd machine, https://www.test.com/test.php, and the web page does show up. So, I am thinking that the include doesn't work and that I should be using something like "<a href="">" instead but the problem is this file, "test.php" is just a bunch of functions. Anyone know? THanks!