Raspberry pi GPIO.add_event_detect crash - raspberry-pi3

Question

i have just recently started to play around with raspberry pi and
cannot understand what is happening using GPIO.add_event_detect feature.
The basic program detects when GPIO16 drops due to button press, prints a message, sleeps 1 second and then prints another message. i switch off and on event_detect during callback to avoid switch bounce causing additional callbacks. The issue is however after only two button presses the program crashes??
This happens every time i run the program. GPIO.VERSION '0.6.2'
Here is the program:
import RPi.GPIO as GPIO
from time import sleep
GPIO.setmode(GPIO.BCM)
GPIO.setup(16, GPIO.IN, pull_up_down=GPIO.PUD_UP)
def pressButton(channel):
GPIO.remove_event_detect(channel)
print("Button Pressed")
sleep(1)
print("Button Released")
GPIO.add_event_detect(channel, GPIO.FALLING, callback=pressButton, bouncetime=5)
GPIO.add_event_detect(16, GPIO.FALLING, callback=pressButton, bouncetime=5)
try:
while True:
sleep(1)
finally:
GPIO.cleanup()
And here is the output showing crash after 2 button presses:
Python 3.4.2 (default, Oct 19 2014, 13:31:11)
[GCC 4.9.1] on linux
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>>
Button Pressed
Button Released
Button Pressed
Button Released
>>> ================================ RESTART ================================
>>>
any help appreciated !