Nop. No simple mistakes. That's the first think i check. Single AF point, manual select - center. As i said, either no foreground stuff AT ALL or nowhere near AF point.
Clear object.. with distant subjects this is quite impossible. A wall of trees 100..200m away. Line of horizon 5..10km away. Some gray/yellow walkway in foilage ~50m away. More like clean lines at desired distance.
Unfortunately i have no pictures i could post to illustrate, imagine something similar to this:
But with less foreground objects.
There are clear, contrasty lines far away in the center of frame, but the focus is on something at the very edges of frame or can not be found at all in the image taken.
I have a bad suspicion that this might be issue with k200d, because i experienced similar misbehavior with 30/1.4. In addition with 30/1.4 i could not get infinity lock AT ALL, so i thought the lens was defective and sold it ridiculously cheap as MF.
Another thing that comes into my mind is repeating lines. If you know what TTL Phase Difference AF is and how it works, you know it can get confused with repeating patterns. If the AF system for example chooses to use horizontal line sensor instead of vertical one, it does not measure the phase of horizon line. It takes reading from trees/foliage that can produce very similar repeating lines. Such way the system might match two different lines.