Open E string won't ring properly

[ac1710]

Ok I have a Lakland skyline 4 string bass and I recently fitted a set of new Piccato flats
(Guy on my course gets really cheep piccato strings, £5 for rounds £7 for flats which is fantastic)

All the notes sound fine, including the open G,D and A but not the open E which sounds like it's been constricted some where. The open E doesn't sound muted and it's not touching the neck or the pick ups or anything like that, it's almost as if it's a really old, dead string. But it's brand new like the rest of the strings, which work perfectly. All the fretted notes on teh E string sound fine as well.

I've adjusted the string height at the bridge and that made no difference.

My string height is generally as low as I can get it without getting any buzzing.

Sorry that my explanation isn't that clear, but hopefully one of you guys can help.

[JustDavid]

Did you change the nut when you changed the strings?

[AlembicPlayer]

nut slot, make sure the string is not binding in the slot. file if necessary. if using round wounds, burnish the slot with a piece of that string(E string in your case).