Urgent help about mixture model

Fuping Qian

In my project, I have to use the mixture model in Fluent to simulate tha gas-solid flow field in a cyclone. In my cyclone inlet, the solid particle have a wide size distribution, so I have to treat different size particle as different phase. In my work, I have to calculate the grade efficiency, so I should add five phases at least. I deselect the volume fraction and slip velocity at first, and when the residuals are flat, I select these two terms. However, when I calculated it again, the following errr is listing: Error: Floating point error: invalid number

Error Object: () At the same time, the residuals jump to a high value (for example,10e4).

I don't know what leads to this. Hope someone can help me. Thanks in advance.