What theme are you using? Free or Premium? What calendar plugin are you using? I used to have a problem with finding a decent calendar plugin for wordpress. All of them had some issues and finally, I settled down with a premium theme with build in calendar. It did cost me some $$$ but I was very happy with it. Let me know which theme r u using and which plugin so that I could help you out with ur problem (if I can )
the thing is i have to write php code to make my own plugin such as..the images has to be changed as date or month changes and that plugin has to work in wordpress