Change Button in Ribbon on Ribbon load

I created a custom Ribbon for an Outlook 2007 App开发者_运维知识库ointmentItem. The AppointmentItem can have a custom property. When the custom property is set, a button in the custom Ribbon should be disabled (by default it is enabled).

I tried the _Load function in my custom Ribbon, but the button is still enabled. I can debug it: the string is filled and the button will be disabled, but in the frontend nothing happens.

public partial class Ribbon1 {  
[...]  
    private void Ribbon1_Load(object sender, RibbonUIEventArgs e)  
    {  
        if (myCustomProperty != "")  
        {  
            Globals.Ribbons[Globals.ThisAddIn.Application.ActiveInspector()]  
                .Ribbon1.buttonCollaborate.Enabled = false;  
        }  
    }  
    [...]  
}  

I don't know whats wrong, may be Globals.Ribbons[...].Ribbon1 is not the current Ribbon? Or is there a ribbon_load_finish_method?

I used VisualStudio 2010 and .Net 3.5

Thanks for your time!

Why go through all the rigamarole? I had to write something similar a while back (for a mail item, not appointment) that required a button to be set based on a registry entry. This was my approach. I'm not saying it's perfect, but it worked for me.

Here's a snippet from my (sloppy) code:

string taglineActive;
OLRegistryAddin buttonSet = new OLRegistryAddin();  // variable for reading the value of the registry key
UpdateBody msgBody = new UpdateBody();  // method for adding/removing tagline from the message

private void Ribbon1_Load(object sender, RibbonUIEventArgs e)
{
    taglineActive = buttonSet.RegCurrentValue();  // retrieve the current registry value

    if (taglineActive == "0")
    {
        // tagline is off for all messages
        ActiveAllMessages.Checked = false; // uncheck "All Messages" button
        ActiveAllMessages.Label = "Inactive - All Messages";  // change the label
        ActiveThisMessage.Visible = false;  // hide the "This Message" button
        ActiveThisMessage.Enabled = false;  // deactivate the "This Message" button
    }
    else if (taglineActive == "1")
    {
        // tagline is on for all messages
        ActiveAllMessages.Checked = true;   // check "All Messages" button
        ActiveAllMessages.Label = "Active - All Messages";  // change the label
        ActiveThisMessage.Visible = true;   // show the "This Message" button
        ActiveThisMessage.Enabled = true;   // activate the "This Message" button
    }