Here, in question and answer form, are some situations that might arise when you are working in a Scientific Notebook document.
Alternately, when you need space, you can use Insert + Spacing, choose Horizontal Space or Vertical Space, and choose an appropriate size space. If you check Custom Space, you can specify the width or height of the space.
If you are in mathematics, you may not need more space. Scientific Notebook automatically spaces mathematical symbols appropriately for most situations. To keep a mathematical expression meaningful for computation, be sure any added space stays in mathematics mode.
If that does not solve your problem, click Maple, choose Settings, General page, and check the setting for Error Level. With a setting of 0, you get no response to errors. With a setting of 1, you get a warning sound with an error. With the higher settings, you get messages with information about the error—usually the error message generated by Maple. (Click Maple settingsDM1-3.tex#Maple error levels for more detailed information about error levels.)