fluent网格检查老出错怎么回事？

我将一个UG建的实体转化为parasolid格式导入gambit中，划分网格，最后fluent检查网格的时候说non-positive face area exist，请问这是怎么回事？
我只做了体网格没有做面网格，但是划分体网格的时候不是面也被划了网格吗？
出错信息如下：

Domain Extents:
x-coordinate: min (m) = 1.989044e+00, max (m) = 1.050000e+01
y-coordinate: min (m) = 9.024512e-01, max (m) = 3.097549e+00
z-coordinate: min (m) = 6.000000e-01, max (m) = 4.400000e+00
Volume statistics:
minimum volume (m3): 1.072129e-04
maximum volume (m3): 2.605906e-03
total volume (m3): 4.000932e+01
Face area statistics:

WARNING: non-positive face area exist.

minimum face area (m2): 0.000000e+00
maximum face area (m2): 2.619216e-02
Checking number of nodes per cell.
Checking number of faces per cell.
Checking thread pointers.
Checking number of cells per face.
Checking face cells.
Checking bridge faces.
Checking right-handed cells.
Checking face handedness.
Checking element type consistency.
Checking boundary types:
Checking face pairs.
Checking periodic boundaries.
Checking node count.
Checking nosolve cell count.
Checking nosolve face count.
Checking face children.
Checking cell children.
Checking storage.
Done.
WARNING: Grid check failed.