Image Calibration: No correlation between master dark and target frames?

[boonejames]

I am getting this ** Warning message when I am trying to calibrate my flats with my darks and bias frames. Is this something I should be fixing or will the flats be correctly calibrated?

Thank you!

[Duncan]

I see this also sometimes.

My understanding is that it's not an issue; all it means is that the dark optimization algorithm has determined that the optimum dark scaling factor is zero, so is applying that ie no dark subtraction. If the flat frames are sufficiently short exposure times, this may happen a lot depending on the camera.