CapacitiveSensorDue issues, read() method always return -1

Hi! I am having trouble making CapacitiveSensorDue library works on DUE.

Here is my code

#include <CapacitiveSensorDue.h>
/*
 * CapitiveSense Library Demo Sketch
 * Paul Badger 2008
 * Uses a high value resistor e.g. 10M between send pin and receive pin
 * Resistor effects sensitivity, experiment with values, 50K - 50M. Larger
 * resistor values yield larger sensor values.
 * Receive pin is the sensor pin - try different amounts of foil/metal on this
 * pin.
 */
CapacitiveSensorDue cs_4_2 = CapacitiveSensorDue(4,2);	// 10M resistor between pins 4 & 2, pin 2 is sensor pin, add a wire and or foil if desired
void setup()					
{
	Serial.begin(9600);
}

void loop()					
{
	long total1 = cs_4_2.read(30);
	Serial.println(total1);			// print sensor output 1
	delay(50);					// arbitrary delay to limit data to serial port
}

Everytime total1 equals to -1 and I don’t know why.

Actually I tried different resistor values between 1M and 8.6M but it doesn’t change nothing.
I attached to this post the circuit sketch

same issue for me... any luck?

Does that library set the pinModes? If not then by default the pullups will be
enabled!!

Had a look in the library, it appears to be trying to set pin modes in the constructor, so
it likely is broken, as that sort of stuff should be done in a begin() method after the system
has initialised. (AFAICT).

Try setting pinMode for your pins in setup ().

doesn't change anything.