I am currently trying to split an address range for a puzzle (64) into different chunks, add to a python list and randomly choose the chunks until they are all complete without sequentially cracking the range. I have a problem with some keyspaces though where I get an error from bitcrack.

for example

--keyspace 00000000000000000000000000000000000000000000000085ffffffffffffff:000000000000000000000000000000000000000000000000857fffffffffffff

Which are the decimals:

Start: 9655717601082343423
End: 9619688804063379455

Bitcrack errors with:  [Error] Error --keyspace: Invalid argument

Any idea why?