Serial3 Does not work

Hi I am having trouble with the Serial3 pin and was wondering if anyone has similar experiences?

I have tried doing a simple input and output on the Serial pin and there is no response on the oscilloscope. I did the same test with the same program on Serial1,2,USB and all of them produce outputs.

Has anyone run into a similar problem? I notice Serial3 is a high current pin set, does this do something I dont understand?

Serial3 works fine here.

Post your test sketch.