problem about communication between 6.4.2 and 6.3.2 version

Hi,

I have two computers with 2 versions of postegresql
    A : 6.4.2
    B : 6.3.2

If I'm on B, I can connect database from A.
But impossible to connect B if I'm on A
    Connection to database failed
    Unsupported frontend protocol.

I do that in TCL, with the patch libpgtcl

Thanks
F.PELLE
--
+---------------------------------------------------------+
+ Telescope Bernard Lyot  pelle@AlphaPcTbl.pic.obs-mip.fr +
+                 FAX     : (33)05.62.95.10.70            +
+                 Tel     : (33)05.62.95.82.27            +
+ CNRS - Observatoire Midi-Pyrennees  (FRANCE)            +
+---------------------------------------------------------+