I think you should stick with the RbmBinaryImage plug-in. Writing your own HTTPHandler is far more difficult. If it's displaying the images on the first page load, then the problem has to be elsewhere. You need to start setting breakpoints in your code and step through it to see what's going on. Start by setting one at the first function that gets called after clicking the pager control. I don't have the data to duplicate your project and test it on my end.