Accessing Iproperties using c#

[navbor]

Hello All,

I am using some code from the June 2010 "Mod the machine" posted by Brian Erkins.

I keep getting an error in C# (express 2010), Please see attached screen dump.

I don't see any obvious difference in my code when compared to Brian's (in fact at one point I copied and pasted his code and still had the same error). Has something changed in the object model, or am i simply doing something stupid?

Please could someone give me some pointers. I am a newbie, trying to learn and am a little stumped with this so any assistance would be much appreciated.

Here is the code:

private void button1_Click(object sender, EventArgs e)       

{           

Inventor.Application invApp = null;           

invApp = (Inventor.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Inventor.Application");

Inventor.Document doc = invApp.ActiveDocument;           

Inventor.PropertySet customPropSet;           

customPropSet = doc.PropertySets["Inventor User Defined Properties"];

.............

.............

[YuhanZhang]

The code is assuming that you have a document opened in Inventor, if you don't this would raise the exception. You can either open a document in Inventor manually or open a document in the C# code before acccessing its property sets.