ngui only displays pink boxes (embedded graphics problem?)

new to unity, using 3.5.6, downloaded ngui the other day. i havent done anything with textures yet. cant find anything from google, forums. someone on the ngui support board asked about GLES but i dont know what thats for. heres what im doing. delete main camera ive dragged an atlas (with a blue cube icon) into the widget tool's atlas spot, same for font. select, say, sliced sprite, dark, 'add to' > panel (pink square shows up) no matter what i change, depth, color, scale, x/y pos. it stays pink. camera preview, scene view, game view. still pink. what could i be missing? embedded graphics? where are settings for these kinds of things?