You need to make an IK solver. There won't be one automatically (yet).
As for IK/IKA: IKA's were the name given to the old armature system. When someone talks about IKA's, it's sort of like they're talking about the 0.5 version of armatures. IK refers to Inverse Kinematics, the calculation of the position of bones in a chain dictated by the location of the endpoints. It differs from the other method of bone placement, Forward Kinematics (FK), in which each bone in a chain inherets its position from up the chain.
How to make an IK solver:
1. Have a chain of bones.
In purple edit mode (TAB):
2. Select the endpoint (not the root) of the last bone in the chain.
3. Snap the cursor to this point (Ctrl-S)
4. Extrude a new bone from this point (e-key)
5. Create a new bone at the cursor point. Name it chain.acc.
The extruded bone you made in 4 is now a part of the IK chain of bones from 1. It will be your IK solver. The bone that created in 5 is not linked to the other bones. It will be your controller (thus the .acc suffix that I use to mean "actuator").
In pose mode (blue edit mode, Ctrl-TAB):
6. Select the extruded bone.
7. Move the the constraint buttons (the chain links)
8. Click Add
9. Choose IK Solver from the popup menu that appears
10. In the OB field that appears, type the name of your armature (case sensitive, and at this probably just "Armature")
11. In the BO field, type chain.acc
Select the chain.acc bone in pose mode, move it around and you should have working IK!