Why does this sequence of actions not work?

For reasons I do not understand, this sequence of actions does not work.

The image is found perfectly and the left mouse button is pressed and held. If I deactivate the last two actions and move the mouse by hand, what is supposed to happen happens. :thinking:

The mouse should be moved horizontally. However, it is moved vertically.

Edit: All good, it also needs a short delay before the last action. For whatever reason this is necessary.