Error Deserializing Xml to Object - xmlns='' was not expected

I am having real trouble trying to deserialize some XML and was hoping someone can offer some assistance. I have read a lot of similar posts but I am unable to resolve this.

XML I am attempting to deserialize

<register-account success="false">
  <user-name>xxxxx</user-name>
  <password>fghgh</password>
  <email>test@example.com</email>
  <error>
    <errorcode>120</errorcode>
    <errormessage>The password is invalid</errormessage>
  </error>
</register-account>

Class I am trying to deserialize to:

[Serializable, XmlRoot(ElementName = "register-account", Namespace = "MyNamespace")]
[XmlType("register-account")]
public class RegisterAccountResponse
{
    [XmlAttribute("success")]
    public bool Success { get; set; } 

    /// <summary>
    /// Gets or sets the Tennant email address
    /// </summary>
    [XmlElement("email")]
    public string Email { get; set; }

    /// <summary>
    /// Gets or sets the tennant password
    /// </summary>
    [XmlElement("password")]
    public string Password { get; set; }

    /// <summary>
    /// Gets or sets the Tennant username
    /// </summary>
    [XmlElement("user-name")]
    public string Username { get; set; }

    /// <summary>
    /// A Tenant Portal error relating to the RegisterAccountRequest
    /// </summary>
    [XmlElement("error")]
    public QubeError Error;
}

Deserialization Method

    public static T Deserialize<T>(string data) where T : class
    {
        if (data == null)
        {
            return null;
        }

        if (data.Trim().Length == 0)
        {
            return null;
        }

        var ser = new XmlSerializer(typeof(T));

        using (var sr = new StringReader(data))
        {
            return (T