GT-511C1R - Fingerprint Scanner not working

I have a problem with the working of a finger scanner. I have connected the scanner good. It works with a library that sends hexadecimal numbers trough a TX to the RX on the scanner. I have tested this following testcode (which was included with the scanner). This code is for the blinking of the background LED on the scanner. The hexadecimal code for the LED is 0x12 with is sended to the scanner through the bool SetLED.

#include "FPS_GT511C3.h"
#include "SoftwareSerial.h"
FPS_GT511C3 fps(4, 5);

void setup()
	fps.UseSerialDebug = true;

void loop()
	fps.SetLED(true); // turn on the LED inside the fps
	fps.SetLED(false);// turn off the LED inside the fps

The only output on my serial monitor is this:

FPS - Open
FPS - SEND: "55 AA 01 00 00 00 00 00 01 00 01 01"

It seems that the only executes the first line of the code and does not go any further…
I have no idea how to let the program continue this code. Is it a bad communication? (I work with 9600 baud) or is my scanner broken or did the scanner not give any feedback?

I hope someone can help me

included: The datasheet for the GT-511C1R

GT-511C1R_datasheet_V1 5_20140312.pdf (425 KB)