My board can't start

I am experimenting the 7 segment display on a breadboard,but the circuit just can't start,but when I touches the capacitor that connect the crystal,it start,when my hand left the capacitor,it can hold for a few second and it stop again,what happem?

the schematic and program is in the melab example page

http://melabs.com/samples/PBP-mixed/7segment.htm