He should of started looking for something which would generate a spark when struck with his carbon steel knife, such as a nodule of Flint or Pyrites. Flint is usually dark-grey, blue, black, or deep brown in colour, and often has a glassy appearance. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. The tinder he should have then used should have been the blackened wood dust results from the failure to light a fire from the friction fire lighting.
The failure to light a fire by just friction methods would have simply been down to the humidity and the type of wood available to use. The truth about friction fire lighting is that almost impossible without the right wood, technique and favorable conditions. There is an assumption that any wood which can be located and prepared can be used to make fire. Some assume that it is just down to finding some hardwood and softwood and take it from there. Mahogany wood for instance is useless for friction fire lighting. A lot of people assume that the so called primitive peoples just have this skill to light a fire anytime anyplace they find themselves, they do not. Just as everyone here on the forum may EDC a ferrocerium rod and striker, these folks will carry with them their favorite wood fire block, stick and bow, usually around their necks in a leather bag ensuring that the wood is always bone dry. The wood block is the most important piece of wood and the wood that has been found to best for friction fire lighting is from Ivy or even Walnut. The best stick being from bay-laurel.
Further info on fire lighting can be found here at
http://snowy.arsc.alaska.edu/gutenberg/1/4/6/8/14681/14681-h/14681-h.htm#ch22The Stone Age was in reality the Flint Age.