macbook pro 3 beeps after installing new memory

Hi, I recently upgraded my ram in a 2009 MacBook pro and when I turned it back on I started getting the 3 beeps with nothing on screen. I saw other people had the similar issue, however mine seems to be a bit different. If you hear one beep, repeating every five seconds, it means your iMac cant detect any RAM. Carried out a troubleshoot of ram and slots below. Macs also come with their own built-in memory tester. If you recently replaced or upgraded the memory, check to see if it. To use it, restart your device and hold down D while it boots, then youll be. I reinstalled old ram in both slots and got 3 beeps and nothing on screen. Then only installed new ram in bottom slot leaving top slot free. The Macbook I have is a mid-2009 and has OSX El Capitan. I am pretty sure this is not about RAMs not being inserted properly, or dusty slots etc. because when I try one of the new (4GB) RAMs with one of the old (2GB) RAMs, it works fine. I have already tried 2 different sets of 4GB RAMs, one couple was second hand, the other pair brand new Crucial. Press the power button to shut down your Mac and wait for a few seconds. They are 204-pin DDR3 SO-DIMM 1600 (PC3L 12800) RAMs, which seems to be the correct kind. Hold down the power button until you see the startup options and the Options gear icon. Hit Command + D to run Apple Diagnostics mode. Press down the D key on your keyboard during your Mac startup. Release the key when seeing a progress bar.

Some info: Macbook info: Macbook pro 13 inch (mid-2009) unibody. I have already tried almost all different combinations between these 6 RAMs (2 old 2GB, and 4 new 4GB).

proc.: 2.26 ghz intel core 2 duo (penryn) ram: currently 2x1gb 1066 MHz Pc3-8500 DDR3 SO-DIMM. So in ended up buying this kit from corsair. The kit did not work, I was 99 sure I bought the right memory. Any 6GB combination, regardless of which RAM uses which slot, also works fine. This machine supposed to be upgradable to 8GB. When it's 4GB or 6GB, it works fine, although a bit slow since I installed El Capitan, which is why I'm upgrading the memory.

Macbook pro 3 beeps after installing new memory