Trial heist - what am I doing wrong?

It takes two clicks, one positions LockPick dude, the other locks him in. It has a visual when it happens.

Annoying design

This is two years later, but I was having the same problem. I tried a little more detail. After I put the contract in the receptacle I clicked on the locksmith. I double clicked and still didn't work, so I focused and tried a little different tack.

I put the cursor over the payment amount as if I was agreeing to that split, then I double clicked very fast and it worked. Just clicking on the portrait doesn't do it.

There are two different scenarios.

For a normal contract you have to click on the portrait, select the person you want by clicking on them.

For green or orange contracts you normally have to go visit the sponsoring person and then go back to initiate the contract using the above method. The sposoring person is named on the contact and usually has a yellow alert over him.