some problems about the DSPLIB64+ fft function

Hi,

       Now,i donwload a DSPLIB64+,and use its fft16x16 function to do some signal's fft by DM6437,but i find if the input signal is a sine wave signal ,its fft amplitude of two symmetrical points will be taken to the maximum amplitude value and the other point is very small,like  the two peaks，but why the output is like this ?

      attatched is my program.1440.fftdsplib.zip

Thanks.