lattice command

Dear lammps dev

I have a silicon carbide lattice with primitive vector

a(1) =   1.54035000 -2.66796446   .00000000
a(2) =   1.54035000  2.66796446   .00000000
a(3) =    .00000000   .00000000 15.11740000

when i put the negative vector, it seems got error, how should i proceed?

What is the error?

Steve