When i first tried Cibachrome, I carefully blacked out my kitchen darkroom, prepared the slide in the enlarger and tentatively opened the paper. I slid my hand into the packet, pulled out a sheet of paper ans cut approximately one inch off for test strip. I exposed and processed it, whipped it out of the fixer and switched on the lights. No image appeared, it was just black. After trying again a couple of times i thought i'd bought some duff paper or chemicals. It wasn't until i put my hand back into the packet that i realised i'd been trying to print on the packing card!
Live and learn, eh...