Oracle's Asset Management interface can be challenging in defining associations at lists.

To assign an employee to an operation within a work order in Oracle's Asset Management interface you need to select the employee with both:

1. the radio button in the Select column shown above at the far left
2. the checkbox in the Assign column shown above at the far right

 
 

If need to check both and then click "Apply" or else the assignment just won't happen. Oracle's interface is... interesting in this regard. You get to the screen above to begin with by finding a work order at the Work Orders tab, going to the Details tab within the Operations tab at the work order, and then changing the "Select Row:" setting to "Assign Employee" before pressing the Go button.

Addendum 6/21/2013: You don't need to check the radio button, just the checkbox.