When using the 9 patch, it sometimes works and we get the result we want. e.g. below is something cut up (which we don't have the font for):

Then in the preview, it looks like this:

And on the device like this:

Once I did it and it worked exactly in both preview and on the device, but I wanted to change the cut lines slightly, so did exactly the same process again and it fails now. with the above result. In both cases i just said "use a file", then set the markers- didnt change any other value (except possibly the auto Scale to DPI which I never know what to chose from - no idea if an iphone 5 (for which the images were made) is high, very high or hd for example.
The image is exactly the right size for the button (i.e. the width of the screen).
I have had this problem with most of the buttons I have cut - they end up half height, losing the text, or end up repeating when they should not.
Any ideas?