This question already has an answer here:
So at some point in the new Doctor Who, The Doctor mentions that he would be able to sense whether or not there were any other Timelords across time and space. However, throughout the series, he doesn't sense any of these Timelords and part-Timelords:
The Master, Jenny, River Song, The Doctor-Donna, Rassilon and his council, etc.
Is there any reason for this besides "timey-wimey" or "Doctor Who has no canon"?
Also, can anyone give me the episode name and the exact quote?