C#.Net - Connect LDAP - Issue in add/remove group

I am developing an automated process that Add/Remove groups from particular account in LDAP based on condition.

I have used C#.Net and used Directory entry namespace for LDAP connection. I have SQL Server connection and gets all the Group distinguished names from database.

I followed below steps:

1.  Connect to LDAP

2.  Filter particular Account

3.  Get member of Property

4.  Add Group (Add Group distinguished name)

5.  Close connection.

I am able to read but not write the group.

When I try to add group, it throws below error.

Error: General –Access denied.

Note: User ID and Password has ADMIN rights for particular OU.

I have below code for LDAP connectivity.

de = New DirectoryEntry(domainADsPath + "/dc=vds,dc=enterprise", username, password, AuthenticationTypes.None)

I tried all the authentication types.

My user id and password all the ADMIN rights. Still I am not able to add group

I have below code for adding group

OpenConnection()

GroupADSPath=”CN=FS-DiabetesTest,OU=Groups,OU=Users,OU=US 55 Corporate,ou=pharma,dc=vds,dc=enterprise”

            de.Properties("memberof").Add(GroupADSPath)

            de.CommitChanges()

            de.Close()

            ‘Here Group name is FS-DiabetesTest

Any Help?