We have installed a new circuit breaker to the box for an addition in our home. After wiring the first outlet to the new circuit we tested and do not have power to the outlet. After checking the breaker making sure it was not tripped and double checking the connections on the outlet, we still do not have power to the outlet.

Absolutely nothing else is on this circuit; no switiches, no GFCI's.

I am about to check with a voltage tester to make sure power is there (in the receptacle and to the screws on the receptacle.

Any other ideas to check?

Well lets get some stuff just a tad clearer please.

You installed an circuit breaker to your existing main service panel.

What type and size cable or conductors did you use from the main service panel to the receptacle outlet? Did you connect the black wire to the brass screw on the receptacle and the white to the silver screw? Is ground connected properly? What type breaker did you use? What type of extension did you build? If this is for living space such as a den, bedroom, living room etc. did you install a AFCI breaker? What size breaker? What is the anticipated load for this breaker?

Did you pull a permit for this work?

While using a voltage tester is okay, I prefer to use a multimeter to get the readings.

Make sure the breaker is fully seated. Are you sure the neutral is properly connected? Tighten the hot connector well? Measure voltage at the breaker to neutral or ground bar. Should be 120VAC+. If you are getting 120VAC then the outlet is not connected properly or the wire has a break in it.