Matching chromosomes can be challenging because of several reasons. One of the main challenges is that chromosomes are very small and difficult to see under a microscope. Additionally, chromosomes can have many similar features, making it difficult to distinguish between them. Moreover, human error in counting or identifying chromosomes can also lead to inaccuracies in matching them. Finally, different types of stains and preparation methods used to view chromosomes can affect their appearance and make it harder to match them accurately. All of these factors can contribute to the difficulty in matching chromosomes.