BIOS unable to detect both of my 4GB RAMs

[Fluctorissia]

Hello! I decided to upgrade my RAM on my laptop by buying an additional 4GB stick to the 4GB I'm currently using. I made sure to buy the same type (capacity, frequency, voltage-wise), but I can't seem to get it to work.

My laptop has 2 RAM slots. I've tried inserting one stick at time (first the new and than the old one again) in both slots to make sure both slots are enabled and both sticks are working. However, when I insert both the sticks at once, BIOS and Windows show only 4GB, and I can't access the other RAM at all, not even through HWiNFO summary. I can't seem to be able to switch RAM amount in BIOS. According to crucial.com, my laptop should support up to 8GB, so that shouldn't be a problem.

The laptop is PackardBell EasyNote TS-11HR.
OS Windows 7 64-bit
Motherboard Packard Bell SJV50_HR BIOS date 03/16/2012
RAMs are both 4GB, 1333 MHz, 1.5 V

Any ideas on how to make my computer recognize both sticks, are there any additional steps I should follow?

 

[spooky2th]

What are the model number of each stick of RAM? Looks like there is enough difference so that they will not work together.

Even if the sticks were the exact same model, there is no guarantee that they will work together. manufacturers will not warranty that.