Access control from another form

Hope you can help me understand what I'm doing wrong.

From the mdi form, on item selection in the combobox,  I want to make linlLabel visible in another form. See code below. Cannot set the visible property.

//mdi form
private void toolStripComboBoxProject_DropDownClosed(object sender, EventArgs e)
        {
            frmTM f = new frmTM();
            f.GeneralCommentsLinkIsVisible = true;
        }
//Child form
public bool GeneralCommentsLinkIsVisible
        {
            get { return linkLabelComments.Visible; }
            set { linkLabelComments.Visible = value;}
        }

wesley