^^^ tonytr1687, That's not correct. Xavier had no problems in X1 telepathically communicating to Logan. "Where are you going?", "Over here", etc.
As to why Xavier couldn't sense Scott's death? Simple. Xavier is a powerful mutant, but his powers have a limited range. As I understand it it doesn't go very far beyond the grounds of the mansion. 1-3 miles at most? Which is why he needed to go to the train station to have a stand-off with Magneto and control Toad and Sabretooth instead of just doing it from the comfort of his office while sitting in shorts and a t-shirt. He was obviously able to sense Jean/Phoenix, but then by definiton so was every other telepath on the planet. Something bad happening to Scott on the other hand is a bit more quiet of an event. If he was nearby, he would have. But considering that Alkali Lake is about 2300 miles from Westchester, that becomes a very faint signal to pick up indeed. I suppose he could have tried looking for Scott using Cerebro, if in fact he had Cerebro. However, after what Stryker did to it, Cerebro probably looked like a luxury car parked in a bad part of Broolyn: sitting on cinder blocks, with its radio, seats, headlights, hood ornament, and battery missing.