Problem with TreeNodeCollection.ContainsKey()

I'm creating a plugin for an application which works with a concept of families. Each Family belongs to a FamilyCategory and each Family contains FamilySymbols. A nice tree structure like that:

• FamilyCategory (Doors)
  • Family (External Doors)
    • FamilySymbol (Door 2000x1000)
    • FamilySymbol (Door 2000x900)
  • Family (Garage Doors)
    • FamilySymbol (Door 2000x2000)
    • FamilySymbol (Door 2100x2000)
• FamilyCategory (Windows)
  • Family (Single Windows)
    • FamilySymbol (Window 1000x1400)
    • FamilySymbol (Window 800x1400)
  • Family (Double Windows)
    • FamilySymbol (Window 2000x1400)
    • FamilySymbol (Window 2100x1400)

Now I'm trying to build a TreeView representing that structure. I have a list of Family objects and each of them has a FamilyCategory开发者_运维知识库 property. I'm trying to determine if a TreeNode with FamilyCategory name already exists and if it does I'm trying to add the Family to that node. If a node for that category doesn't exist I create a new one and add the family there. Unfortunately the code below always evaluates categoryExists as false.

foreach (Family family in families)
{
    string familyCategoryName = family.FamilyCategory.Name;

    bool categoryExists = treeView.Nodes.ContainsKey(familyCategoryName);

    if (categoryExists)
    {
        categoryNode = treeView.Nodes[familyCategoryName];
    }
    else
    {
        categoryNode = new TreeNode(familyCategoryName);
        treeView.Nodes.Add(categoryNode);
    }

    TreeNode familyNode = new TreeNode(family.Name);

    categoryNode.Nodes.Add(familyNode);

    foreach (FamilySymbol familySymbol in family.Symbols)
    {
        familyNode.Nodes.Add(familySymbol.Name);
    }
}

What am I doing wrong?

try replacing this:

categoryNode = new TreeNode(familyCategoryName);
treeView.Nodes.Add(categoryNode);

by this:

categoryNode = new TreeNode(familyCategoryName);
categoryNode.Name = familyCategoryName;
treeView.Nodes.Add(categoryNode);

(TreeNodeCollection.ContainsKey() searches the Name Property, not the Text Property)