Learn English – Which preposition follows “lack of knowledge”

It could also be that "knowledge of" goes with a person or shows one's familiarity with someone or something (cf. the verb kennen in German) and "knowledge on" or "knowledge about" (cf. the verb wissen in German) goes with a field of study or a broad subject where one's personal attachment to it is irrelevant.

It also seems that "knowledge about" could be used in either case; it's just a longer form that may not be desired if someone's trying to write poetic verse or a terse newspaper headline, for example.

You can inquire with or of (someone), at (a place), or into (something), so:

A previous inquiry with / of Bob did not yield any new insights.