Ron Troyer on "[Plugin: WooCommerce - excelling eCommerce] WooCommerce - Cannot add a Variable Product to Grouped Product"

Is it only possible to add a "Simple Product" to a "Grouped Product"?

In other words I have a group of four products that are related - one of which has two flavors. The product with flavors is a variable product.

I can add the three simple (non variable) products to the grouping but not the variable.

This seems like a simple and obvious capability - am I missing something?

http://wordpress.org/extend/plugins/woocommerce/