Okay after some more testing....
now i got this:
Arduino: 1.6.5 (Windows 8.1), Platine: "Arduino/Genuino Uno"
In file included from C:\Users\Philipp-PC\Documents\Arduino\libraries\SerialPort\SerialPort.cpp:20:0:
C:\Users\Philipp-PC\Documents\Arduino\libraries\SerialPort/SerialPort.h: In member function 'size_t SerialPort<PortNumber, RxBufSize, TxBufSize>::write(const __FlashStringHelper*)':
C:\Users\Philipp-PC\Documents\Arduino\libraries\SerialPort/SerialPort.h:583:11: error: 'prog_char' does not name a type
const prog_char* p = (const prog_char*)s;
^
C:\Users\Philipp-PC\Documents\Arduino\libraries\SerialPort/SerialPort.h:584:25: error: 'p' was not declared in this scope
size_t n = strlen_P(p);
^