XBEE Antennas and their range
So range is a function of a lot of stuff (see another answer about this topic here), but my wild guess here is one of two things.  Either you aren't providing something to your circuit that you are meant to, or you have something in your area which is generating a lot of noise.

Most Zigbee devices operate in the 2.4GHz range, which these days is pretty saturated.  Microwaves, wifi, X10 cameras (anyone still have these? mine stopped working once wifi became popular), etc.  And on top of that, the proliferation of cheap non-FCC certified ebay electronics from China means that there are lots of things which are terrible throwing noise out into the spectrum.  My friend had a fake Dell laptop supply he got off ebay which generated nearly 30V on ungrounded metal surfaces in a radius of about 5 feet!

So there are two good ways to check this:


Go out to a park or something where there is less likely to be things generating lots of RF noise and see if you get more range
Get an old AM radio and tune it to a station which is filled with static.  See if it gets a lot louder or quieter when you unplug/plug in things around your apartment/home.  If you find something which makes a dramatic difference, that may be the issue!


Second suggestion: if you have a circuit with a different Zigbee which works with a much greater range and a different Zigbee module, try swapping this one in and see if the range is better.

Third and final suggestion: turn down your bitrate.  Slower transmission is general easier and less error-prone transmission.  Don't think that Zigbee actually has a way to slow down the wireless chunk of the transmission process, but if it does it may help.

If all else fails: maybe you have a dud?  Try returning it?