guga
7
i’m not sure this helps but: when in chromatic mode, press either the retrig+/retrig- buttons to change the octave (you should be able to see four different colors (yellow, cyan, blue and purple which is the lower octave)
if this is not the case, then try and set the current sound to play your sample chromatically (hold function and press sample button for instance), from the menu’ that will appear you can choose whether the loaded sample should be played chromatically or not (same goes for the synth)
if none of the above answered your question or helped in any way…mmm,have you looked in the manual? 
edit: ok, i read you managed to set the sample to play chromatically…question is: are you trying to play the sample with a keyboard? bear in mind that you can access only four octaves on the AR, just in case