Texture Atlas with GUI - problem

Hi everyone
I’m trying to make a GUI with pictures. With the “Gimp” I did texture atlas so I have one texture for the whole GUI. I read on this forum that I can any part of the image from my texture atlas placed anywhere on the GUI (eg a button) using UV’s parameters
All what I need is “Graphics.DrawTexture” or “GUI.DrawTextureWithTexCoords” function.

Unfortunately, no matter how I change values ​​in these functions always appears on the screen the whole texture. (in other places, stretched or suppressed, but always the whole texture.) I do not know what’s going on.

I would ask for help.

I’ve used DrawTextureWithTexCoords to display portions of an atlas:

	GUI.DrawTextureWithTexCoords(mouseRect,instance.cursor,Rect( frameNumber * 0.25,0,.25,1 ) );

The image is four frames across, so I use .25 as the ‘step’ (1/4). Zero and one indicate the top and bottom of the image, and the .25 indicates the width of one frame.