When you select Deep Sky as your target type (when creating or editing a target), you must give a target name that ACP will recognize at observing time so it can look up the target's coordinates in its catalog.
You'll see a button Search Names next to the Deep Sky target type selector. Use this to validate your deep sky object names locally before submitting your plan to ACP. The MiniSAC catalog (installed with Planner) is the same one used at the observatory by ACP, so if the name is found while using Planner, you can be assured that ACP will be able to identify it and retrieve the object's coordinates for you later.
When you click the Search Names button, the Search Deep Sky Catalog appears. Here's what it looks like:
The purpose of this window is to assist yo in choosing a target name that corresponds to an object in ACP's deep sky catalog. It works as you'd expect: enter a partial object name and click Search, then a list of possible matches appears. Click the one you want and the OK button will be enabled. When you click OK, that exact name will be put into the Target Name field of the Add/Edit target form.
You have a choice of searching for names beginning with what you put into the search box, or listing all the names that contain what you put into the search box.
In the catalog, most objects are listed by their catalog name, followed by a space, then the catalog number. For example, Messier 51 is listed as "M 51" (with a space). So to search for all M objects (and not MGC etc.) put in a search term of "M " (with the space). This will cause only M objects to be listed. Play with this and you'll get it.