I got the following 3 isomers of C5H9N correct:
I also got the following fourth isomer (ignore the blue dot, it was a slip of the pen!)
However, the given answers has the following 2 other isomers instead of my single one:
Could anyone advise me where I went wrong? What did I do incorrectly and more importantly, what could I note to avoid making the same mistake again? E.g. is there a particular method to follow when drawing all the isomers?