Using RTC module DS1302 for Mega 2560 & Due

I have some problem that would like to ask for your help.
I'm successful that I used RTC module DS1302 for Arduino Mega 2560.
And my RTC module DS1302 (SCLK,I/O,RST) set to (4,3,2).
The code is....
DS1302 rtc(2, 3, 4);
The result is successful.
Monday 12.04.2010 -- 12:12:20

But if I use the same RTC module DS1302 and code to upload for Arduino Due, the result is not complete .
The result just appear week.....
Monday xxxxxxxxxx -- xxxxxxxx

How should I change my link pin between DS1302 and Arduino Due??
(the attachment is my RTC module DS1320.)

RTC DS1302.jpg