The same process worked for the RLC Parallel Circuit example MapleSim model. See below. Not sure why it's not working for the DoublePendulum model.

@Rouben Rostamian  Yes, the equations provided were the result of using MapleSim's linearize function (see https://www.maplesoft.com/support/help/MapleSim/view.aspx?path=MapleSim/LinkModel/Linearize&cid=1582). Here is a screenshot of the worksheet used to generate the equations.

DoublePendulum.msim

I figured out that it was a licensing issue. Thanks.