i made the nether portal and put a sign under it with a button near activated it and it only stayed lit for 10 secs then went out and when i went out i heard a glass breaking sound im just wondering is this normal or and if not how do i fix it please answer asap!!!
Placing the sign under the portal and activating it with a redstone signal is a feature of MyM servers. It will activate the portal of your choice (that you unlock with specifically required items) long enough for you to enter and then break. If you chose not to go through once you activate it, you will actually experience it breaking, rather than not seeing it at all.