iphoto won't install

I have just upgraded to Yosemite and have been trying to install iphoto. Whenever I do it downloads a file to my applications folder which is only 452kb. Meanwhile, in the Appstore it says it is "Installing". That is all that happens. It goes on for quite a while with nothing else happening and I can only seem to stop it by restarting the computer.

Any advice would be greatly appreciated.