hashcatGUI Error: no digests loaded

[dw-sec]

Hi Guys,
I am quite the newb to hashcat so please bare with me...

I have a machine running 2 AMD Radeon HD6900's in a Xfire config. Win7 X64

Hashcat-GUI > oclHashcat tab

Trying to crack WPA key, I have converted the cap from aircrack to hccap, loaded it in under the hashfile field, set the following options
HashType: MD5
Left Rules: Dictionaryfile.txt
Right Rules: ?d?s
Charset 1: ?d?s
Resources...
GPU Dev: 0
Workload tuning: 8
Loops: 256
watchdog: 90

Whenever I try to run this I get the following

oclHashcat v0.26 by atom starting....
Error: no digests loaded

it then pops me back to the command prompt.

When I try to run the same options through the oclHashcat-plus tab I get:

Error: hash: KIT, line length exception: 3
Error: no hashes loaded

any ideas?

thanks