I think keith383 had the problem that I had too in the beginning. If the character set is reduced to only letters and numbers, there's a 'chance' that the generated password will not include any numbers. Especially if it's only six or eight digits.
There're several ways around:
Use a number as prefix or suffix. (this will fix it for every site)
Increase the length of the password.
Use a modifier for that site, until the password shows a number.
Put more numbers into the character set.
Do anything else that lets PasswordMaker generate a new password.