auto length increment?

[qweasd]

I'm trying to bruteforce an md5 hash of a MAC address. Here is my command line:

Code:

cudaHashcat-lite64.exe test.txt --custom-charset1=0123456789ABCDEF ?1?1:?1?1:?1?1:?1?1:?1?1:?1?1

I know for a fact the format and length of the input. So why is it doing lower length first? eg:

Plain.Text...: ****1:0F:4C:1