Troops get left at base in wars

I would very much appreciate someone explaining to me why some of my troop and my cc war troops don't come with me into battle.

Today, for example, only 7 out of my 10 dragons came, and the 5 hog riders in the cc decided not to come. They were certainly ready to go, and they were waiting for me when I got back - so no mistake on my part. However I did terribly -got no stars and let the clan down for no apparent reason.

Am I missing something?

Please help:unsure:

Thanks

What the heck is this thread doing in troop and spell ideas. this is where people say things like "we should add a new troop-the rat!" not problem solving