added statement to prevent that DataError and Asymmetry CmdArg are called for the same plot - illegal to combine these arguments
added statement to prevent that DataError and Asymmetry CmdArg are called for the same plot - illegal to combine these arguments

e5-tu-do/DooFit,e5-tu-do/DooFit,e5-tu-do/DooFit,e5-tu-do/DooFit