Hilbert Transform

Hi

I wonder if anybody knows this:

Supposed I have a complex function of ydata + i ydata1. The following is the command I typed:

make /N=100 ydata
•setscale/I x,0,10,ydata
•ydata=1/((x+3)^2)
•Display ydata
•hilbertTransform /DEST=ydata1 ydata
•setscale/I x,0,10,ydata1
•ydata1*=-1

Now I want to make sure that I could get back ydata, if I hilbert transform ydata1.

•hilbertTransform /DEST=ydatacheck ydata1
•setscale/I x,0,10,ydatacheck

However, you can see from the picture 1 attached that ydatacheck is different from ydata.
May I know why is this so? How can I improve this?
pic_0.jpg