here is a srcset attribute for img but it doesnow work. on over 400px wievport and under 400px viewport inboth, there is only /images/imedi.png shown. but i put both option

<div><a href="/imedi-live/"><img title="imedi live" src="/images/images2/imedi.png" alt="imedi live" srcset="/images/images2/imedi.png 400w, /images/imedi.png 800w" sizes="(max-width: 400px) 400px, 800px" /> Imedi</a></div>

i put srcset="/images/images2/imedi.png 400w, /images/imedi.png 800w" sizes="(max-width: 400px) 400px, 800px" to shown one .png when under 400px and second .png when over 400px.

but only one of this photo is being shown.