It seems to react to the torch on the left sensor but not on right sensor.
Do you have a voltmeter?
If not then it could be worth using the following hardware setup:
one sensor => one ADC input => read value (as decimal) =>use rprintf to print value to UART
If you dont hava a TTL serial to R232 card yet and/or breadboard then I suggest you buy one (or make using MAX232) its a great debug tool as you can then output to Hyperterminal/RealTerm on your PC.
Then you can use your PC to act as a multi-meter.
If all fails then my advice is dont get for Sharp IR detector They are too precise. You need something with a wider detector beam - ie sonar mounted on a servo so it can scan. Check my vid http://www.societyofrobots.com/member_tutorials/node/280
Although written in C++ its also very simple in C.