Help with driver question

Ok, I think I am confused...I hooked up my LM1084 as a CCS with a 0.68ohm sense resistor and used a six string diode test load with a 1 ohm resistor to measure voltage drop across the resistor...I consistently measure 0.6v across the resistor....my online calculators tell me with a 0.68R sense resistor in a CCS configuration I should get 1800mA....am I doing something wrong? Shouldn't I expect a 1.8v drop across my test load 1R resistor? Or am I going about this wrong? What is my driver running at with the reading I am getting?
Thanks!
Jeff

What's your supply voltage? 6 diodes is way too many. You need 3.

7.4v...this is for a 445 diode...thought the voltage drop across all the diodes should be near the same as the laser diode....

Yes, it should. And that's why you want 3, not 6.