My keyboard won't let me put a negative Declination in the Planner. Steps to duplicate:
1. Go into Observe > Planner. Select Bright Nebulae and Dark Nebulae for Object Type
2. In the Restrict to Ranges section, click in the field for "Declination in Degrees". A keyboard pops up with a button that is labeled ".-". When you click on that button it gives you a periond "." instead of a minus signt "-". Give it the values -26 to -27. You'll notice it returns .26 to .27.
3. Click in another field to set the values just described. Then click Do Search at the bottom.
Nothing is returned because those are invalid values.