VeeJay,
The USB-6008 can supply 8.5 mA on the digital lines which should be enough to activate a solid state relay. The Crydom spec says input current is ~3-20 mA. At 5 V the current should be less than the USB-6008 can supply.
I think your problem has to do with the way you set up the DAQ Assistant. I cannot help with that. Post your code in the other thread as Dennis asked and someone will likely be able to help you.
Lynn