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The RTC Routine of STM32

Good afternoon~everybody
Please allow me to express my appreciation to you for taking time to read my post.I am a new hand in the electronics. And I met some troubles now.Could you give me some suggestions?
Maybe my question is simple for you.
The chip I used is STM32F100 and I use RTC routine from atom. But my program always shows:
while (RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET)

What’s wrong? How to solve it?
PS: This is data-sheet of STM32F100: http://www.kynix.com/uploadfiles/pdf8798/STM32F100C4T6B.pdf  Please have a look if needed.