How to simulate click event on IHtmlObjectElement in C++?

[FoxBryant]

I want to simulate click event on object element in php page to upload a file. The object's html like this:

Now, I can get the object's pointer and can get it's properties correctly, but when call click method, it returns S_OK without any effect, the upload dialog doesnot appear. I doubt where the question is, can somebody help? Thank you for your time.