Symantec Management Platform (Notification Server)

Been trying to import machines into a filter from a csv file and having no luck. Haven't been able to find anything on connect. But when I try and select my csv file and hit save nothing changes in the filter. Does the csv file have to be formatted a specific way?

You really only should need a single column, with just machine names. If the machines aren't in the system currently (as managed agents) they won't import either.

Machine names are the only option? Would serial numbers work?

which aren't visible. The only option I've ever seen work in all versions of Altiris are computer (or user) names.

I haven't experienced this on SMP7 yet, but in NS6 this used to happen if you had the .CSV file open (in Excel, Notepad, etc) when you tried to import it.  It produced this exact issue where you select the file and nothing happens (no error, etc).  Like Jim said, you can only import computer names into this interface; if you have a file of serial numbers, you'd need to use Connector (or whatever it is called now in SMP7) to import I believe.