Unlocking cores on the old AMD chips is never a guaranteed thing, because your CPU could be one of three things.
1. Your CPU is just a single core, there is no 2nd core to unlock.
2. Your CPU is actually a Dual core with one core disabled. The reason why this is is because sometimes the demand for single core chips were higher than dual cores, so all AMD did was disable the cores on some surplus dual core stock and sold them as single Cores.
3. That CPU is a Dual Core, but one of them is defective so AMD just disabled the defective one and sold it as a Single Core.
Basically, you have a 1/3 chance of actually being able to get another core.
IMO, if you want more performance do it by just getting a better processor. Throwing a Phenom...