MSE not found in Scenery Library & Compatibility

Have just bought and installed my first MegaSceneryEarth V.2, Florida.

The scenery looks fine but I have no comparison.

Have a lot of pay-ware airports and other add-ons like Aerosoft Manhatten X, FSGlobal 2008, UTX America, GEX America/Canada etc.

I am thinking op buying the New York State MSE.

Are there any compatibility issues which may cause interference with other add-ons.

On forums it states that airports must be higher in the Scenery than MSE, I presume they mean the Library.

MSE is not showing in the Library but when I want to add Florida manually (which is not in the main FSX folder but on the same HD)

to the Library I get a message that it is already there.

Any information is more than welcome.

EDIT: Found Florida in Scenery Library, usually new scenery is on top but this was a long way down.