There are several possible causes of incomplete or missing penstrokes in your drawings.
Making sure that the Slate is digitizing your drawing
First, verify that the Slate’s upper LED shines purple while you are drawing. A purple LED signals that the Slate is digitizing your sketches and drawings.
If the upper LED turns purple but the marks are not visible in the app, there may be a temporary Bluetooth connection problem that you can solve by consulting this article about connecting your Slate to your iPad via Bluetooth.
If the problem persists, refresh the Slate by pressing and holding the New Page button at the top of the Slate until the blue LED blinks red. Make sure that all magnetic objects, including the Pens and the Ring, are at least 10 inches or 25 centimeters away during the refresh. You will now be able to write on your paper or notebook.
Type of notebook used
The Slate works with any sheet of paper or a notebook up to 3/4 inch | 1.5 centimeters thick.
For the best possible experience when using a notebook, make sure that the notebook sits flat on the Slate and contains no metal parts.
A notebook or drawing pad with a top-bound cover is ideal since it allows the paper to sit flat on the Slate.