Unable to Plate Solve Images

[Knight of Clear Skies]

I never used to have any trouble with this, but now I'm finding neither Astrobin or Astrometry.net seem to be unable to plate solve most of my new images, despite being taken with a variety of lenses on my camera and a borrowed modded one. Don't suppose anyone has any suggestions please?

Edit - I'll post some example images that will and won't solve later, I'm just trying a few more to see if I can spot any sort of pattern. I'm wondering if something I'm doing in my processing is confusing the solver.

[lensman57]

I never used to have any trouble with this, but now I'm finding neither Astrobin or Astrometry.net seem to be unable to plate solve most of my new images, despite being taken with a variety of lenses on my camera and a borrowed modded one. Don't suppose anyone has any suggestions please?

Edit - I'll post some example images that will and won't solve later, I'm just trying a few more to see if I can spot any sort of pattern. I'm wondering if something I'm doing in my processing is confusing the solver.

I  just tried Astrometry.net with a fits file of NGC 6823 and it failed. 

A.G

[Knight of Clear Skies]

Had a try with a selection and it seems that most of my 135mm images do solve - the ones that don't have comet Jacques in them which could confuse the solver maybe? it seems to have more trouble with my wider fields. I'll try processing them differently to hide the fainter stars and see if that helps.

[Earl]

I have found that images taken to early in the night struggle to solve, then as soon as the right level of darkness kicks in, bingo fixed.

[tingting44]

my images do not solve with CR2's but solves fine with jpeg's ...