what are you doing?
it looks very simple when you know what you do, but in newbie world it is very hard.
what it looks like you did was try and change the size of the player and you removed one or more of the sections of the player.
there should be a left a center and a right section you can change the size of them to anywidth you want if you are just using the same height.
but you do not just use the whole background image in the one section.
you pick the background image in the first part of the player settings then you will go back and pick the part of the background image that goes in to each of the 3 sections, you have to use the cross hair guide to adjust the different sections on the image of the background. the numbers have to match in the code section dreadm posted in his screen shot. doing this 3 section thing is how the player is allowed to stretch.
when you adjust the cross hair targets make sure you remember the numbers they are at so you can write them in the section of the code.
the computer uses those numbers to know where to start and end each section it only uses the background image you make as a map for it to use in what the player looks like. you will also need to make sure the buttons are in the exact pixel locations for them to work proper and look good.