[lqy]

Hello everyone.
I was doing the heat sink's simulation by using phonics FLAIR. The case was that one fan made air blow into the channels of a heat sink. The fan and the heatsink were all placed in the one duct. But every time when I just start to solve the case one window will pump out saying:

'Error. Unrecognised material in cut cell
Note: In instances of multiple process failure only the first error is reported.'

All the materials I used are the default materials in earth file, so I really don't know what does this mean.

Could anyone give me some clues about this error? I really need to solve this problem as quickly as possible.
Thank you very much in advance.