Web Browser control is not working in Windows 7

Hi,

I am opening a pdf using web browser control in a win forms application I am using Navigate method.

webBrowser1.Navigate("https://serverurl");

Server url returns pdf return type is html. Also I am using pdf open parameters for search & highlight

the text, every thing works fine windows xp(I have tested 32 bit) I can able to open pdf in the 

web browser control but in Windows 7 64 bit web browser control is blank and asking the program

to open then opens as a PDF as we open normal pdf in windows but the expectation was to open 

the pdf in web browser control with search text highlighted.

Any idea why web browser control not able to open pdf inside web browser control in  Windows 7 ?