Python random.expovariate() zero division error

When I use random.expovariate(1/6) in my code, i get zero divison error. Anyone knows why? This is my code:

randomSeed = 1000
random.seed(randomSeed)    
def function1(env):
    for i in range(1000):
        time = random.expovariate(1/6)
        yield env.timeout(time)

This is the error:

File "..\simulation.py", line 108, in function1
    time = random.expovariate(1/6)
File "..\random.py", line 440, in expovariate
    return -_log(1.0 - self.random())/lambd
ZeroDivisionError: float division by zero