How to reproduce: partial class Form2 { /// <summary> /// Required designer variable. /// </summary> private System.ComponentModel.IContainer components = null; /// <summary> /// Clean up any resources being used. /// </summary> /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param> protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } #region Windows Form Designer generated code /// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { this.radTrackBar1 = new Telerik.WinControls.UI.RadTrackBar(); ((System.ComponentModel.ISupportInitialize)(this.radTrackBar1)).BeginInit(); this.SuspendLayout(); // // radTrackBar1 // this.radTrackBar1.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right))); this.radTrackBar1.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(233)))), ((int)(((byte)(240)))), ((int)(((byte)(249))))); this.radTrackBar1.Font = new System.Drawing.Font("Segoe UI", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0))); this.radTrackBar1.LabelStyle = Telerik.WinControls.UI.TrackBarLabelStyle.BottomRight; this.radTrackBar1.LargeChange = 5; this.radTrackBar1.LargeTickFrequency = 139; this.radTrackBar1.Location = new System.Drawing.Point(36, 69); this.radTrackBar1.Maximum = 140F; this.radTrackBar1.Minimum = 1F; this.radTrackBar1.Name = "rTrackBar1"; this.radTrackBar1.Size = new System.Drawing.Size(243, 33); this.radTrackBar1.SmallTickFrequency = 5; this.radTrackBar1.SnapMode = Telerik.WinControls.UI.TrackBarSnapModes.None; this.radTrackBar1.TabIndex = 0; this.radTrackBar1.Text = "rTrackBar1"; this.radTrackBar1.ThemeName = "ControlDefault"; this.radTrackBar1.TickStyle = Telerik.WinControls.Enumerations.TickStyles.None; this.radTrackBar1.Value = 80F; ((Telerik.WinControls.UI.RadTrackBarElement)(this.radTrackBar1.GetChildAt(0))).MinSize = new System.Drawing.Size(100, 0); ((Telerik.WinControls.UI.TrackBarBodyElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1))).Margin = new System.Windows.Forms.Padding(7, 0, 7, 0); ((Telerik.WinControls.UI.TrackBarScaleContainerElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0))).Orientation = System.Windows.Forms.Orientation.Vertical; ((Telerik.WinControls.UI.TrackBarScaleElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2))).Orientation = System.Windows.Forms.Orientation.Vertical; ((Telerik.WinControls.UI.TrackBarScaleElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2))).StretchVertically = false; ((Telerik.WinControls.UI.TrackBarLabelContainerElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1))).StretchVertically = false; ((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(0))).Text = "Lo"; ((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(1))).Text = "Hi"; // // Form2 // this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; this.ClientSize = new System.Drawing.Size(822, 515); this.Controls.Add(this.radTrackBar1); this.Name = "Form2"; this.Text = "Form2"; ((System.ComponentModel.ISupportInitialize)(this.radTrackBar1)).EndInit(); this.ResumeLayout(false); this.PerformLayout(); } #endregion private Telerik.WinControls.UI.RadTrackBar radTrackBar1; } Workaround: remove setting of the text from the designer file to the Shown event of the form public partial class Form2 : Form { public Form2() { InitializeComponent(); } protected override void OnShown(EventArgs e) { base.OnShown(e); ((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(0))).Text = "Lo"; ((Telerik.WinControls.UI.TrackBarLabelElement)(this.radTrackBar1.GetChildAt(0).GetChildAt(1).GetChildAt(0).GetChildAt(2).GetChildAt(1).GetChildAt(1))).Text = "Hi"; } }