IMHO logically you need:
$Count = 1
Reason is that if multiple lines are selected, you need to inform the user that only one should be selected.
But $Count>=1 works too, it will only not generate an error and select the first in the list.
I Suppose it wil b:e
$Count > = 1
As I suppose that if there is more than one it takes the first one (with the head activity) and pass it (with the sow page) to the next page...