Thermal Transmission Tool Failure

[Rheumer Rachel]

Hi,
We are running WuFi Pro 6.8 to model new build external wall models which are made up of an insulated timber frame with an OSB sheathing faced in a breather membrane and a mineral fibre cavity insulation slab, then a 50mm ventilated cavity and an external facing brick skin. The timber frame is insulated with Frametherm 32 glass fibre slabs and is then faced internally in 50mm PIR board faced in an Intello Plus airtightness barrier. A service zone is located internally faced in plasterboard. Initially the balance 1 & 2 results were spot on and the water content and RH results looked believable however the Thermal Transmission tool does not then operate and a dialogue box appearing with the message 'Floating point division by zero' No matter what we have tried nothing has so far made a difference. Can anyone suggest how this can be fixed please?