It might not be compatible. Did you make sure it was certified for your hardware? Maybe your motherboard does not support 1333Mhz or 1600Mhz RAM (especially if stock RAM was at 1066Mhz). And speed isn't the only thing to look at, not all RAM are equal, some will use different voltage (1.35v, 1.5v, etc...), some will use different latency (CL8, CL9, etc...).
Dell, HP, Acer, etc... systems are always more picky for RAM. I recommend going to the Crucial website and enter your Dell model and it will automatically suggest RAM that is 100% compatible. Kingston website also has a similar feature. Corsair website probably has it too. Of course you can also buy it directly from the Dell website and it will also suggest RAM that is compatible.
Bottom line, you cannot buy any RAM without verifying compatibility first. If it's not too late I would simply return the RAM and get reimbursed.
Not sure if flashing BIOS to latest version might help in this situation.