My built in flash pops up, even though my speed light is connected?

I have a nikon d3100 and I recently bought a speed light for it, but when I take pictures with it, I realize that the built in flash pops up, not fully but the head does raise up a little. Is that normal or not, or is there a setting in my camera I should change to let it know that the flash is connected? Really need an expert.

You neglected to tell us what electronic flash you are using.

If you did not choose the manual mode of exposure, the on-board flash may be automatically turning on.

Nikon SB 400 or newer flash units do not trigger the on-board flash.

I just tested a SB600 on a D300 in all the different P A S M modes. The on-board flash does not open and with the external flash off the camera, the on-board flash does not automatically pop up either. I guess when you own a D300, Nikon expects that the photographer knows when they need to use a flash

If you're using a flash which is TTL compatible (any of Nikon's modern flashes from the SB400 to SB900 and some third party units), the built-in flash will not (should not) pop up for any mode.

If you're using a third party "dumb" flash (non-TTL), then you need to get your camera off of the Auto mode and in to Manual. In Manual, shutter, aperture, and program modes, the flash will not come up automatically. Of course, when using a dumb flash, you can only shoot in manual or aperture priority modes.

Experiment with Nikon D90 and SB600.
Camera exposure mode set to Auto, indoors.
If SB600 is turned off, built in flash pops up. If SB600 is turned on, built in flash does not pop up. Same result whether SB600 is set to manual or TTL.

Generic, manual, non-TTL flash? Http://keerok-photography.blogspot.com/2012/08/how-to-use-generic-flash.html