Unresolved import error despite extern mod module

Unresolved import error despite extern mod module

So I'm trying to compile some code, but I'm getting a compile time error
on an import from crate extra despite the use of extern mod extra;. Here
is the output from the compiler:
zhttpto.rs:10:4: 10:13 error: unresolved import: there is no `uv` in `extra`
zhttpto.rs:10 use extra::uv;
^~~~~~~~~
zhttpto.rs:10:4: 10:13 error: failed to resolve import `extra::uv`
zhttpto.rs:10 use extra::uv;
^~~~~~~~~
zhttpto.rs:11:12: 11:18 error: unresolved import: there is no `net_ip` in
`extra`
zhttpto.rs:11 use extra::{net_ip, net_tcp};
^~~~~~
zhttpto.rs:11:12: 11:18 error: failed to resolve import `extra::net_ip`
zhttpto.rs:11 use extra::{net_ip, net_tcp};
^~~~~~
zhttpto.rs:11:20: 11:27 error: unresolved import: there is no `net_tcp` in
`extra`
zhttpto.rs:11 use extra::{net_ip, net_tcp};
^~~~~~~
zhttpto.rs:11:20: 11:27 error: failed to resolve import `extra::net_tcp`
zhttpto.rs:11 use extra::{net_ip, net_tcp};
^~~~~~~
error: aborting due to 6 previous errors
And here are the import declarations from the code:
extern mod extra;
use extra::uv;
use extra::{net_ip, net_tcp};
use std::str;
Is there some reason that the compiler can't find the selected modules?