Different Icon in the taskbar

I installed VB6 application using our installation package.
If run the application program, icon is displayed in the taskbar.
And I changed my application's icon, compiled it and replaced existing execution file.
If I run the application program, old icon is still displayed.
I reboot PC but still new icon is not displayed.
I don't know if this is a program problem or installation problem or OS problem.
Can anybody give me any advice?