I am trying to update a photo for the employees in AD using the following code:

public static void AddPictureToUser(string strFileName)
    {
    // Open file
    System.IO.FileStream inFile = new System.IO.FileStream(strFileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);

    // Retrive Data into a byte array variable
    byte[] binaryData = new byte[inFile.Length];

    inFile.Close();

    string ldap = "LDAP://COMPANY.COM:389";

    string userAuthToMakeChanges = "user";

    string passwordUserAuthToMakeChanges = "password";

    string employeeUsername = "usernameToFind";

    System.DirectoryServices.DirectoryEntry directoryEntry = new System.DirectoryServices.DirectoryEntry(ldap, userAuthToMakeChanges, passwordUserAuthToMakeChanges, AuthenticationTypes.Secure);

    DirectorySearcher query = new DirectorySearcher(directoryEntry);

    query.PropertiesToLoad.Add("thumbnailPhoto");

    query.Filter = "(&(objectClass=user)(sAMAccountName=" + employeeUsername + "))";

    SearchResult result = query.FindOne();

    System.DirectoryServices.DirectoryEntry user = result.GetDirectoryEntry();

    // Clear existing picture if exists
    user.Properties["thumbnailPhoto"].Clear();

    // Update attribute with binary data from file
    user.Properties["thumbnailPhoto"].Add(binaryData);

    user.CommitChanges();
}

But I am receiving this error: System.DirectoryServices.DirectoryServicesCOMException: ‘A constraint violation occurred.’

No more details

I don’t think the problem is related with the access because I can change the employee data with though this tool. https://www.codetwo.com/freeware/active-directory-photos/?sts=1327 What do you think is happening? Thanks in advanced!