MPC design and linearizarion

Hello! I am working on designing an MPC controller in Simulink as part of my master's thesis. Unfortunately I do no thave a lot of experience with Simulink. The finished MPC regulator will have 3 manipulated variables, 2 measured disturbances, and 1 measured output. When I click the design option, the MPC design task launches, and everything seems to be going fine until it comes to the ''...linearizing the plant...'' task, and the error message ''...Could not linearize. You may consider first obtaining a linear model from a Linearization task and then using it in MPC design...'' pops up. The strange thing is, the models (that apparently cannot be linearized) are state space models that are imported from the workspace. They are linear. I have a hard time understanding why Simulink gets caught up on this step. I have included a two screen dumps of the model in question. What do I need to do to get past this step and move on with my project? Thanks for any and all help, please ask if any additional information required to answer this question!

Thanks! John

In the plant model I am attempting to controll(called H3-18MW), are following state space models: