[9fans] starting 9vx in FreeBSD :Shared object "libthr.so.3" not found

[alasdair]

Hi, 
on starting 9vx inside FreeBSD with the command"./9vx.FreeBSD -u glenda"
I get the following error:
/libexec/ld-elf.so.1: Shared object "libthr.so.3" not found, required by
"9vx.FreeBSD"

I came up with a blank on searches in 9fans lists and on the net generally
for a solution.

Would welcome any help to solve this.

Thanks,

Alasdair