help need with adding multiple lights in one scene

Hi guys

need a little help with lights in unity, the problem is that i have to add multiple lights in my scene, im able to add two lights but when i duplicate or add third light one of the previously added lights gets turned off, im not able to figure out why.

any help on the same will be of great use thanx

In the menu under Edit/Project settings/Quality you can change Pixel Light Count.

Hey thnks a ton really was getting frustrated bout this thnk again