Close-Up Sharpness

I’m using a high-resolution digital camera and just started photographing trees, bark, leaves, etc. Many of my photos don’t show good resolution in the small details, such as bark texture, the small veins in leaves or the edges of paint peels. I shot images today using a tripod, mirror lock and cable release, and I used an f/11 aperture on a 100mm f/2.8 macro lens. The image looks soft in several places. Is what I’m seeing a problem with digital capture?