error: IRsendDemo does not compile with IDE 1.5.5

Most probably you will get a compile error saying:
'IRsend' does not name a type

Obviously, there is a conflict between some of the new Arduino libraries.

Moving or removing (only if you are sure you never will need it) of the RobotIRremote folder that comes with 1.5.5 will solve the conflict.

contact: nji(at)