Previously Edited Value Graph Values Missing?

[Lydia5CA5]

While editing a video in After Effects, I used the value graph to make the transitions more dynamic. When I went back to make adjustments to the graph, it presented itself as a straight line instead, yet the video still acts as if it's still properly graphed. Any idea what's up with that? Here's my graph + the settings I'm currently using on it for reference, though I don't know how much it will help. 

[Jose Panadero]

Start by deactivating the Show Animated properties so AE will show you only the selected animated parameters. The Show Animated Properties displays all the animated properties of the selected layer and could cause these "straight" lines when you are seeing more than one animated property displayed. Then, you must be sure that you have at least 2 keyframes on the animated parameter and tha values of every keyframes differ. Two keyframes with the same value will show you a straight line.