wpkg = "CN=" + pkg + ",OU=Software,OU=Groups,OU=blah blah";
//wpkg = "LDAP://CN=" + pkg + ",OU=Software,OU=Groups,OU=blah blah";

**// the following code works and finds what I am looking for****
DirectoryEntry entry = new DirectoryEntry("LDAP://" + ouPath);
DirectorySearcher search = new DirectorySearcher(entry);
search.Filter = "(CN=" + cn + ")";
search.PropertiesToLoad.Add("memberOf");

SearchResult result = search.FindOne();
**This finds the computer I am looking for**
if (result != null)
{
DirectoryEntry entryToUpdate = result.GetDirectoryEntry();

entryToUpdate.Username = un;
entryToUpdate.Password = pass;

**I want to add a value to the memberOf property**

entryToUpdate.Properties["memberOf"].Add(wpkg);
entryToUpdate.CommitChanges();

***I get System.DirectoryServices.DirectoryServicesCOMException:  "The
**server is unwilling to process the request.**
**regardless if I have "LDAP://" in wpkg or not

entryToUpdate.Invoke("Add", new object[] {wpkg});
**I get System.Runtime.InteropServices.COMException: "Unknown name. Exception from HRESULT:0x800200006 (DISP_E_UNKNOWNNAME))"**
**regardless if I have "LDAP://" in wpkg or not

entryToUpdate.CommitChanges();

//entryToUpdate.Properties["memberof"].Value = "";
//entryToUpdate.Properties["memberof"].Clear();
entryToUpdate.Invoke("remove", new object[] { wpkg });