Got ninjaed but...
Are you sure you know how to actually add an "Else" event, besides adding it from System when adding a new event? Just asking to make sure. You can also right click an event block (the left side), go into "Add", and select Else at the bottom of the list that pops up.
Otherwise, some types of conditions are not available if certain conditions are in an event block. Some examples is that there can only be one trigger per branch (Usually "On X" or anything with a rightfacing green arrow), and things such as trigger once or on key pressed may not be available depending on what type of conditions are present in an event block. Try tinkering with your events to figure that out, i.e remove, check again (by attempting to add else), and either undo/redo.