crocus not blooming

I moved into a house and there's tons of crocus in the garden... one group bloomed, but there are several square feet where the crocus haven't bloomed... Now the tulips are blooming aroud here and the trees are getting leaves. Any ideas as to why the crocus haven't bloomed? They never bloomed last year either.

Could it be that they are a fall-blooming crocus?

I have quite a few that are showing foliage now, but bloom in the fall. They can be planted eight inches deep which allow other plants to grow in the same area during the summer. Are there other plants growing in the same area that may make it difficult to notice the fall blooms?

That's a good thought, but I didn't see them blooming last fall, and they are at the corners of the flowerbed, so it would be noticeable.