There was another case, a rather unusual one. Another victim with yet another note predicting future events have been found, and Sherlock was in his thinking mode. With his usual cold and distant demeanour, he walked into the crime scene confidently, and scanned the surroundings. How fascinating. Oh, how he loved cases where he could actually use his thinking skills.

When he spotted you, he immediately deducted everything he had to know. That's why he completely ignored you.