Most likely you have geometry and/or meshing problems.

I'll assume that you've performed (not just reviewed) the tutorial "Flow Over a CO2 Dragster" to familiarize yourself with Caedium.

Review "12 CFD Tips for a Productive New Year", especially:

• "Sequence your CFD preparation according to geometry, surface mesh, volume mesh, physics assignment, and post processing. Each step relies on the previous step, so if you skip directly to the volume mesh only to find you need to modify your surface mesh or geometry you will waste valuable time."
• "Create a residual monitor and a variable monitor (e.g., lift, drag, average pressure) to help determine whether your steady-state simulation has converged, indicated by at least a drop of 3 orders of magnitude in all residuals."
• "For external CFD simulations you often need to construct a volume around your object, which means you need to subtract your object from a larger volume representing the outer boundary. This is analogous to the mold you would create to manufacture a casting of your object."

For a detailed Forum discussion on F1 in Schools see "F1 in Schools Problems (Caedium Pro. Issues)".

For diagnostic help see "How do I fix mesh and solver failures?".