Can't add relations between some lines but can for others

Ok so I've been adding relations between different lines in different sketches for quite some time now and this is the first time that I've run across this predicament. I am trying to make Line 1 (in the pictures I've provided) the same length as Line 1 @ sketch 9. However I am not able to do so as shown by the picture. I can however add a relation between Line 1 and Line 7 @ sketch 1. Please help me out. I'm confused pretty badly and I realize that I could just take the dimension from the line I want and enter it in for Line 1 but I need to figure this out.

Thanks in advance!

SolidworksSketching