Color variation problem in Photoshop Elements

I am printing a poster over 4 pages.  The main color is a blue.  In one quadrant the color comes out a lighter color.  I have check each quadrant for the color number with color picker and they are all the same.  Why is one quadrant printing a lighter color.  How can i get this to print the same color.  This is in a sublimation project where all the pieces are put together to make one print larger than my printer will handle.  I have changed everything to adobe rgb color profile.  What else should I look at the get this fixed? In the photograph, the lower right corner is the one that is coming out lighter.  It is harder to tell in the photo, but when it is printed on white fabric, it is a definite difference