What I usually do for such cases is check the link of the image and try to open it in another browser window/tab. If you are using Firefox, just right click on broken image link and select "Copy Image Location" or you may check out the page source as well. Open it in another window/tab and check if that works.
The link to an answer below from one of the article here in CodeProject explains it very well -
There is something about "Paths" for Asp.net beginners[
^]
It says -
A leading / character essentially means that the subsequent path is relative to the root of the web server, while the lack of a leading / means that the subsequent path is relative to the current page's directory.
So according to your code, "Images" folder must be present in the root of the web server. Check the path.
Hope that helps!