function for a single string number of syllables

[tebirkes]

I have a function who takes a single string as argument and returns the number of syllables of some string e.g. str = "I eat pancakes"
But i do not get the correct number of syllables what do I do wrong here? 
I use regular expression module and already got a pattern that describes the syllables in some text

def count_syllables(str):
    pattern = re.compile("[aiouy]+e*|e(?!d\b|ly)[aiouye]?|[td]ed|le\b")

    match_new = pattern.match(str.lower())
    if match_new:
        print len(string)