How do I edit the hyperlinks of an existing ppt file?

I use Impress 4.4.3.2 Chinese version to open an existing ppt file but I can not edit the existing hyperlink. If this is the hyperlink I edit by Impress, I can put the cursor besides the text with hyperlink and use CTRL-K to see the hyperlinks defined previously. But when it is generated by a MS power point, I find the hyperlink dialog box is simply empty when I apply the same procedure above.