Security WB1v4 Task 4.4 Unable to integrate ACS with AD

Hi

Has anyone run into the following problem?  When trying to integrate ACS with AD,as per task 4.4 instructions, I always get the following message:

"Connection test to 'inelab.local' failed.
Further information on status:
- LDAP UDP status error"

I've checked that clocks are synchronized, that the DNS is resolving correctly the inelab.local domain to the AD IP address.  If I type wrong credentials I get an error telling me that the user or pwd is incorrect, so communication is ok between the AD and ACS.

I hope anyone can help.

Best Regards.