ES explorer can't write extSD

Hi ev'body,

If I have no problem for writing on ext SD (Samasung 64Gb) with the stock apk "My Files",
when I try to do it with another file manager (ES explorer for example),
I'm asked to choose the root dir on the ext SD, but this one doesn't appear on the list!
Idem with other FM. Where is the bug?

Thanks for help



6045Y, unrooted
5.0.2-010 06