Photos not being imported to PC

When I want to import photos from my iPad or iPhone, I link them via cable to my PC's USB port. A box then appears saying 'Import photos and videos' and I can then download them into my Photos album on the PC. This box seems to have stopped appearing for some reason and is very irritating. I've seen posts in this forum about going to the iCloud and import the photos from there, but this is a long winded way of doing things and shouldn't be necessary. The last time I imported the usual way, there was no problem and I haven't changed any settings or updated software between then and now. If you have any advice it would be greatly appreciated.

Using iTunes version 12.3.1.23 64 bit

Using iOS9.1 on my iPad

Using iOS 9.0.2 on my iPhone 6