That link at Crucial says this:
"Each memory slot can hold DDR3 PC3-8500, DDR3 PC3-10600 with a maximum of 4GB per slot".
That laptop has 2 RAM slots. Are both slots occupied now? What speed is the RAM in those slots? You say you have 4 GB of RAM now, but I don't know if that is 2 sticks of 2 GB each or 1 stick of 4 GB.