help! URL redirect not working - map 301

Hi all 

I want to map all previous blog links from europeanspodcast.com/episodes/[existing links] to europeanspodcast.com/all-episodes/[existing links]

There are hundreds of existing blog pages so i don't want to manually add each one separately. This is one for example: europeanspodcast.com/episodes/why-give-a-damn-about-the-european-elections

I have added this into the url map: 

/episodes -> /all-episodes 301 

but it hasn't worked. What can i do?