Issues Aligning Images

Posted by courtney13 on Apr 30, 2018; 3:29pm
URL: http://astroimagej.170.s1.nabble.com/Issues-Aligning-Images-tp1002.html

I'm trying to stack some pictures of a galaxies but need to align them before combining into one image. I'm trying to use "align stack using apertures'. It worked for the first galaxy but now after I click to put the apertures on the photo I get the following message:
***ERROR: No signal for centroid in aperture C4 of image MCT20_1803260108_out.fits.
********: Measurements are referenced to the non-centroided aperture location

I've gone back and tried the first galaxy I did again and it comes up with the same message even though previously I managed to do this. Does anyone know how to resolve this?