C# 反射>嵌套属性 getValue >对象与目标类型不匹配

>我无法解决问题，所有值都在对象的第一级很好地恢复，但嵌套属性值生成错误。我确定我需要调整 getValue 参数对象，但我不确定如何调整。我尝试将嵌套属性信息数组，属性信息或req作为参数传递，但仍然出现相同的错误。有什么提示吗？

UpdatePhoneReq req = new UpdatePhoneReq();   
foreach (PropertyInfo propertyInfo in req.GetType().GetProperties())
{
    if (propertyInfo.CanRead)
    {
        string attributValue = "";
        string attributName = propertyInfo.Name;
        Type attributType = propertyInfo.PropertyType;
        if (attributType == typeof(XFkType))
        {
            PropertyInfo[] nestedpropertyInfoArray = propertyInfo.PropertyType.GetProperties();
            attributValue += "{";
            foreach (PropertyInfo subProperty in nestedpropertyInfoArray)
            {
                // --- > the GetValue below generates the error
                System.Diagnostics.Debug.WriteLine(subProperty.Name + "=" + subProperty.GetValue(req, null).ToString());
                attributValue += subProperty.Name + "=" + ",";
            }
            attributValue = attributValue.Substring(0, attributValue.Length - 1) + "}";
        }
        else
            attributValue = propertyInfo.GetValue(req, null) == null ? "" : propertyInfo.GetValue(req, null).ToString();
            System.Diagnostics.Debug.WriteLine("[" + propertyInfo.PropertyType + "]" + attributName + "=" + attributValue);
    }
}