How to configure ldap on grafana 6.2.5

I am currently trying to connect Grafana 6.2.5 to a LDAP server following the instructions:

However when i try to log in Grafana using a existing ldap user i get the following messages on the grafana log file:

t=2020-03-03T14:12:53-0500 lvl=info msg=“Ldap enabled, reading config file” logger=ldap file=/etc/grafana/ldap.toml

t=2020-02-03T14:12:54-0500 lvl=dbug msg=“Ldap Search For User Request” logger=ldap info="(ldap.SearchRequest) {\n BaseDN: (string) (len=57) “OU=User_XXXX,OU=Users,OU=XXXX,DC=XXXX,DC=XXX,DC=XX”,\n Scope: (int) 2,\n DerefAliases: (int) 0,\n SizeLimit: (int) 0,\n TimeLimit: (int) 0,\n TypesOnly: (bool) false,\n Filter: (string) (len=24) “(csAMAccountName=usertest)”,\n Attributes: ([]string) (len=5 cap=8) {\n (string) (len=2) “cn”,\n (string) (len=2) “sn”,\n (string) (len=4) “mail”,\n (string) (len=9) “givenName”,\n (string) (len=8) “memberOf”\n },\n Controls: ([]ldap.Control) \n}\n"

t=2020-02-03T14:12:54-0500 lvl=eror msg=“Error while trying to authenticate user” logger=context userId=0 orgId=0 uname= error=“Invalid Username or Password”

t=2020-02-03T14:12:54-0500 lvl=eror msg=“Request Completed” logger=context userId=0 orgId=0 uname= method=POST path=/login status=500 remote_addr=XX.XXX.XXX.XXX time_ms=26 size=53 referer=

Could you please help me?

Thank you