<AddIn language="CLR" library="MPA_SPARC.dll" namespace="MPA_SPARC">
    <ArcMap>
      <Commands>
        <Button id="Biogeography_Branch_MPA_SPARC_btnAnalyze" class="btnAnalyze" message="Start the main Analysis tool" caption="Analyze" tip="Analyze" category="Biogeography Branch Add-In Controls" image="Images\btnAnalyze.png" onDemand="false" />
Public Class btnAnalyze
    Inherits ESRI.ArcGIS.Desktop.AddIns.Button
    Public Sub New()
    End Sub
    Protected Overrides Sub OnClick()
       
        //the click task
    End Sub
    Protected Overrides Sub OnUpdate()
        Dim KeyExist As Boolean
        KeyExist = (My.Computer.Registry.GetValue("HKEY_CURRENT_USER\SOFTWARE\Biogeography Branch\SPARC", "MPA", Nothing) IsNot Nothing)  And
            (My.Computer.Registry.GetValue("HKEY_CURRENT_USER\SOFTWARE\Biogeography Branch\SPARC", "Resources", Nothing) IsNot Nothing)
        Enabled = (My.ArcMap.Application IsNot Nothing) And KeyExist
    End Sub
End Class
					
				
			
			
				
			
			
				
			
			
			
			
			
			
		onDemand="false />
 onDemand="false" />
					
				
			
			
				
			
			
				
			
			
			
			
			
			
		Protected Overrides Sub OnUpdate() Me.Enabled = My.ArcMap.Editor.EditState <> ESRI.ArcGIS.Editor.esriEditState.esriStateNotEditing End Sub
Late in the game I know, I did however just hit this issue and resolved it by using onDemand="0" instead of onDemand="false"