[gmx-users] how to understand this sentence

[lina]

The Y-size of the box (1.999239) times the triclinic skew factor
(1.000000) is smaller than the number of DD cells (2) times the
smallest allowed cell size (1.000000)

I don't understand the fatal error message it has been given during a
simple run,

I tested with large box already, during editconf I used -d 30 already,

it's a very small peptide, the box dimension is   63.95000  60.76600  62.99900

Thanks