Hello Zenith,
Theoretically, it should be ok to put a button between pin 14 and pin 11 to act as your trigger. Some more information might help us figure out why the trigger is not being registered every time.
1) Is the program set up for rising edge or falling edge triggering?
2) What kind of button are you using?
3) Do you notice any differences between the times when the trigger event is registered and when it is not (for example, the length of time you hold down the button)?
E.Lee
Eric
DE For Life!