ValueError: could not convert string to float: 'Pregnancies'

def loadCsv(filename):    lines = csv.reader(open('diabetes.csv'))    dataset = list(lines)    for i in range(len(dataset)):        dataset[i] = [float(x) for x in dataset[i]    return dataset

I'm trying to implement Naive-Bayes but its giving me this error even though I've manually changed the type of each column to float.it's still giving me error.

Above is the function to convert.