DX surface problems

Hi! Im having some trouble loading an image file and display it as background. When i call: hr = D3DXLoadSurfaceFromFile( g_pBackground, NULL, NULL, "back.tga", NULL, D3DX_FILTER_NONE, 0, NULL ); I get D3DERR_INVALIDCALL error. What em i doing wrong? My idea is to use that function to load a image into a surface and copy it to the backbuffer using CopyRects(). Em i using the wrong functions? Is trere a better way to display backround images and splashscreens.