Unknown error

Why each time I use "click here to add a frame" / "choose Image" / and import a PNG image to form a frame, seems like everything is ok now, but then I restart the proyect and my frame seems like they were cut and expand to the other frames? how I prevent this?
In the pictures appear how Stencyl modified my frames and the secuencia in the resources foder of my game.

Make sure that each 'frame is equal in size.

Let's say your strip is 100w x 50h. You have 5 frames in it. Each frame must be 20w x 10h if you want the animation/strip to look right.