Exactly how many characters is the key supposed to be?

I look at my key from getting the game and the first part looks like a normal key, numbers and letters mixed and with '-' spacing between, and then there is a series of numbers with some spacings. I try entering it in just as its presented into the prompt window but every time the window claims its too long or too short, even adding and subtracting a single space informs me its not the right length.

What am I doing wrong? Should I include the spaces or not? Should I include the '#' symbol like it is in the key or not? Why does it keep informing me that regardless of the length that its too long or short, even when I subtract one space when too long, and add one when too short?

Trying to get the multiplayer key up and running so I can attempt to run the DayZ mod.

I entered the key as it was shown and when I click on change or change and play it simply does nothing.

You need to copy all the numbers and stuff... not just the part that looks like a seriel