A stalwart of the opposition's crusade against the Emergency, Advani was missing at the event organised by Shyama Prasad Mukherjee Research Foundation.
The foundation's treasurer Shyam Jaju, who is BJP's vice-president, insisted that Advani was invited.
Shah declined to answer to reporters' queries on the matter.
Sources close to Advani, who has been marginalsed in the party, declined to comment, saying the question should be posed to the organisers.
In interviews leading to the anniversary of the Emergency, Advani had said that "forces that can crush democracy are stronger", creating a buzz in political circles leading to speculation that it was a barb aimed at Modi.