problems with ssl/TLS configuration in debian testing

[<ximm@vodafone.es>]

Hi,
I've followed all the steps in the link
http://www.openldap.org/pub/ksoper/OpenLDAP_TLS_howto.html
to configure this.
When finishe I've run the test:
$openssl s_client -connect ldap.iespolitecnic.org:636
-showcerts
the following error appears: 
verify error:num=21:unable to verify the first
certificate
verify return:1
5823:error:14094410:SSL routines:SSL3_READ_BYTES:sslv3
alert handshake failure:s3_pkt.c:1052:SSL alert number
40
5823:error:140790E5:SSL routines:SSL23_WRITE:ssl
handshake failure:s23_lib.c:226:

If I put the slapd in debug mode, the messages are:
tls_read: want=5 error=Resource temporarily
unavailable
tls_read: want=5, got=5
  0000:  16 03 01 00 07                               
     .....
tls_read: want=7, got=7
  0000:  0b 00 00 03 00 00 00                         
     .......
tls_write: want=7, written=7
  0000:  15 03 01 00 02 02 28                         
     ......(
TLS: can't accept.
TLS: error:140890C7:SSL
routines:SSL3_GET_CLIENT_CERTIFICATE:peer did not
return a certificate s3_srvr.c:2010

Please, can someone help me with this?

Thank you very much.