I am having a lot of trouble with moving data between two ldap servers, with a GUI tool it really is messy, so I had to use good old fashioned console commands.
1. Export data into an ldif with ldapsearch:
ldapsearch -x -h [hostname] -p [port] -D [adminuserdn] -w [adminuserpassword] -b [searchbasedn] -s sub "objectclass=*" dn objectclass cn sn employeenumber > export.ldif
the stuff coming at the very end of the command is the list of attributes that I want to include in ldif. Default is include all.. If object has some attributes that is not allowed to be imported (like encrypted passwords etc.) you have to leave them out.
2. Import data into the target ldap server:
ldapadd -x -c -v -h [hostname] -p [port] -D [adminuserdn] -w [adminuserpassword] -f export.ldif -S export.ldif.log