Problem to read custom webpart properties (if it's not static)

I have problem with custom properties. I want to set custom boolean value or write custom text. It do not work, if I don't set values to static. However, if I set value to static all webparts share the same values and I don't want that. Example, write text "Demo" in first webpart settings and I open another webpart in another subsite, it contains also text "Demo". But if I remove static keyword, my webpart settings are null. How I can fix this?

Here is my example code:

using System;
using System.ComponentModel;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;

namespace SharePointProject1.WebPart1
{
    [ToolboxItemAttribute(false)]
    public partial class WebPart1 : WebPart
    {
        // Uncomment the following SecurityPermission attribute only when doing Performance Profiling on a farm solution
        // using the Instrumentation method, and then remove the SecurityPermission attribute when the code is ready
        // for production. Because the SecurityPermission attribute bypasses the security check for callers of
        // your constructor, it's not recommended for production purposes.
        // [System.Security.Permissions.SecurityPermission(System.Security.Permissions.SecurityAction.Assert, UnmanagedCode = true)]

        #region Web-Part settings
        public  Boolean _isEnabled; // if this is static, I can read value but all webparts in SharePoint share this value
        [Category("Custom Properties"),
        Personalizable(PersonalizationScope.Shared),
        WebBrowsable(true),
        WebDisplayName("Enable something"),
        WebDescription("Something")]
        public Boolean Ready
        {
            get { return _isEnabled; }
            set { _isEnabled = value; }
        }

        string _pageTitle;
        [WebBrowsable(true),
        WebDisplayName("Page Title"),
        WebDescription("Title displayed on the page"),
        Category("Test Properties"),
        Personalizable(PersonalizationScope.Shared)]
        public string PageTitle
        {
            get { return _pageTitle; }
            set { _pageTitle = value; }
        }
        #endregion

        public WebPart1()
        {
            // Problem read custom properties

            string test1 = _pageTitle; // null
            string test2 = PageTitle; // null
            bool test3 = _isEnabled; // false
            bool test4 = Ready; // false
        }

        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
        }

        protected void Page_Load(object sender, EventArgs e)
        {
        }
    }
}