Custom charset recurrence

[Maxiz80]

Hi.
I'm trying to run this on a powerful machine. But I've no result
mp64.exe -r 2 -1 ?l?d ?1?1?1?1?1?1?1?1?1?1

If i use smaller lenght it's ok
mp64.exe -r 2 -1 ?l?d ?1?1?1?1?1?1?1?1?1
Why?

[Xanadrel]

It's probably just going through all the candidates, checking for the number of occurance of each character each time, and that takes time, also it works with a shorter mask cause the difference in number of candidates is quite huge.