i hooked this up once before but now it doesnt work.

i have a black and white wire that i have running up form the basement out of a junction box. i have it connected to the recept side of the togle switch-outlet (black on copper white on nickle plate screw.) then i have a black and white wire running up the wall to the light i put in. ive tested the power to that wire wire and its telling me i have power to that light but it wont turn on. and yes the light fixture does work and so does the light bulb. i checked them both just minutes ago to be sure. i bought a new switch and outlet and there is a breakoff tab it says that im suppose to remove. can u tell what that is? not sure if its the small white plastic piece or if its the copper tab. thanks