Interfacing with a 12bit DAC (MAX532)

Hi everyone, I am interfacing my arduino with a DAC and one thing is bugging me. My DAC is only outputting negative voltages. It states in the datasheet that the DAC is capable of outputting +/- 12 volts and I am only seeing the -12V to 0V.

There is some reference to unipolar mode and bipolar mode in the datasheet, but I don't know if this is a hardware selectable mode or a software selectable mode. Do I wire the DAC differently for bipolar mode? If anyone could shed some light on this it would be great. here is the data sheet

http://www.google.com/url?sa=t&ct=res&cd=3&url=http%3A%2F%2Fpdfserv.maxim-ic.com%2Fen%2Fds%2FMAX532.pdf&ei=28swR4PwHpeqwwK1qeyJCg&usg=AFQjCNF6OiWuM5q3nDPl82inBX1TNt3uCw&sig2=4D54Z8lRc7dPeKaNXmtLhg

Thanks, Matt

from figure 9 and 10 in the datasheet i can se a wiring difference from unipolar to bipolar mode. In bipolar mode you need an opamp and a resistor that is not shown for unipolar mode.

Are you powering the DAC with a bipolar powersupply ?