C# : The server is unwilling to process the request

Problem:

I am receiving the error "The server is unwilling to process the request" when changing the AD attribute userAccountControl to enable user account in C#. I am using the below C# code to enable AD user account and reset password.

public static void EnableADUser(string username)
{
    DirectoryEntry user = new DirectoryEntry("LDAP://CN="+username+ ",OU=TestOU,DC=TestDomain,DC=com");
    int old_UAC = (int)user.Properties["userAccountControl"][0];

    // Enable User Account
    user.Properties["userAccountControl"][0] = (old_UAC & ~2);
    user.CommitChanges();

    // Reset Password
    user.Invoke("SetPassword", new object[] { "MyP@$$w0rd" });
    user.CommitChanges();
}

Cause:

The cause of the problem is, we are modifying new user attribute before Set the Password. So, we should set the password for new user before making any attribute change. I have changed my C# code to reset password first and change attribute.

public static void EnableADUser(string username)
{
    DirectoryEntry user = new DirectoryEntry("LDAP://CN="+username+ ",OU=TestOU,DC=TestDomain,DC=com");

    // Reset Password
    user.Invoke("SetPassword", new object[] { "MyP@$$w0rd" });
    user.CommitChanges();

    int old_UAC = (int)user.Properties["userAccountControl"][0];
    // Enable User Account
    user.Properties["userAccountControl"][0] = (old_UAC & ~2);
    user.CommitChanges();
}