Q: When I want to send a picture through whatsapp , a message pops up saying "this photo has not yet been downloaded to your iPhone" what does that mean? please i need some help!!

When I want to send a picture that I have taken before 2 months through whatsapp , a message pops up saying "this photo has not yet been downloaded to your iPhone" what does that mean? please i need some help!! I have iPhone 5s