Mike
Like I have told you many times in the past, most of your problems are not "shotmaking issues" as much as they are "position/pattern issues". The first thing I noticed is that your 7 ball is down there and your cue ball is up above the side pocket. Basically you messed up on the position and you will pay for it with the more difficult shot.
Try to notice which side of the pocket you are missing the shot on. If you are missing on the outside consistently, aim to pocket the ball on the inside of the pocket - if you are missing it on the inside, aim for the outside of the pocket.
The space between the two arrows on either side of the pocket is your margin of error for this shot.
Also pay attention to the contact point on the ball. In the diagram below, I have drawn a red line from the center of the pocket, through the center of the 7 ball and out to the rail. I have also drawn a line from the cue ball to the point where the red line goes through the 7 ball... where these two line intersect, that is your contact point. Notice that you need to have the cue ball hit that contact point at the angle in which is it illustrated... if you hit the 7 ball too full on either side of that contact point - you will miss.
The natural angle of this shot is also diagrammed. I have also shown what is called "angle in" and "angle out". This is something that is extremely important with determining the path of the cue ball. I illustrate a "natural pattern" on this shot, and the direction of the ball is determined by the "angle out". When you have identified the contact point and the angle out, then you can control the cue ball by using inside our outside english, low right, high right - whatever. Just make sure that the contact point and the angle out remain the same.
These shots are not very difficult if you learn how to determine the contact point - and the direction the cue ball will take after contact.