I created the following macro that is pretty much identical (aside from mouse placement) to another one I made. The other one works, but this one doesn't. I'm trying to get it to click my mouse on a bookmarklet shown in the 2nd screenshot. The funny thing is, when I first made this one yesterday, it worked. Today, it doesn't. I even deleted it & remade it. No difference.
After moving the mouse to the desired location, it may be necessary to add a brief pause (e.g., 0.2 seconds) then repeat the Move Or Click Mouse action in your macro, specifying a click at 0,0 relative to the Current Mouse Location.
Alternatively, if Firefox has a Bookmarks menu, selecting the bookmarklet there using the Select Or Show A Menu Item would be more reliable.
Ok, I changed it to select menu instead, but it's still not doing anything.
Rarely is it best to click at an "absolute" position, as you are doing:
If the popup that shows the "Annotate" always appears at the same RELATIVE position to its window, then change the Move and Click to be relative to one of the corners of the window. Looks like the right-top corner would be best.
I just wanted to share my result of my 3 hour debugging session of today.
tl;dr Do not in any case use jpg screenshot.
Some ages ago I thought it is a great idea to set apple screenshot to jpg. I forgot, as it barely matters, but today I wanted to use mouse movement with move or click mouse and it failed with the jpeg.
In the shell you can reset it to png with
defaults write com.apple.screencapture type png
killall SystemUIServer
and check if it worked with
defaults read com.apple.screencapture type
took me about 3 hours, as "sometimes" it worked.
Thank's again for this great program, the only way I can help is share my stupidity 
all the best
Juergen