Really?
Yes, really

No lowercase 'L', no uppercase 'o', no uppercase 'i' and no '0' (number zero).
If you used -i (case insensitive) it would have looked for 1koeLen (and 1KoeLen and 1KOeLen and 1KOELen, etc. etc.) - but the number it should have returned should have been very low then (as there's many more possible hits). If you used it with the -r (regex), then I think it accepts all those forbidden characters, but it wouldn't give an estimate of when it would be found (if I recall that correct).
I used -i , i will give it a try with -r too
But thanks to you i have one for myself now

Cheers