Yes. At the beginning of the 3pi-linefollower example, the 3pi calibrates the IR sensors by turning right and left to get the minimum and maximum values of the darkest and lightest parts of your course.
You mentioned that the 3pi-demo-program example worked on your 3pi. Did you run the "Sensors" test and verified that the bar graph, showing the individual sensor outputs, fluctuated as you slid the robot across the line of your course?
The 3pi-linefollower example also displays the same bar graph after calibrating the IR sensors (before pressing button "B" a second time). Can you confirm that the behavior is the same when reading the sensor outputs for both examples (e.g. ranges from 0 to 4000, always read 0, or behaviors are different)? Does anything change if you remove the PC5 shorting block?
If the sensors do not reading anything, then the emitters might be off. Can you use the camera on your cellphone (or a cheap digital camera) to look at the IR sensors while they are on? If the emitters are working, the camera should pick up and display the IR. See the instructions and picture at the bottom of this page for more information.