ATI 9600 and Resident textures

Hi, I’d like to ask people here, if you know that ATI is supporting the resident textures.
My card has 256 MB of memory. I’m loading
16 24bit textures 2048x2048 +
6 32 bit textures of the same size.
Once the textures get drawn on the screen they all remain resident. (Provided that my algorithm for getting this is correct). But how can this be? The card has 256 and the textures I load require 288 MB. Shouldn’t it remove some textures from being resident ( specially, because when the 6 32bit textures are drawn, most of the other 24bit textures are not drawn (at most 4 of them can show up, along with the 6)
Here is my code (JOGL) for setting a button text which indicates the index of the texture, along with if it’s resident or not (“r”):

int[] isMapResident = new int[1];

gl.glGetTexParameteriv(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_RESIDENT, isMapResident);
               mapButtons[textureIndex].getText().indexOf(' '))
               + ((isMapResident[0] == GL.GL_TRUE) ? " r" : " "));