Defining more than one atom with mass and create_atoms command


I have a simple problem that I couldn’t figure out how to solve it by reading the documentation.
In my simulation I have 2 types of atoms,
In lj units I use this command style:
Mass 1 1
Lattice fcc 1
Create_atoms 1 region 1
Mass 2 2.5
Lattice fcc 1.3
Create_atoms 2 region 2

The first type is created but it gives me the error “Numeric index is out of bounds” for mass 2 2.5 line. I tried using just one atom to create the atoms and then try to assign type 2 to those atoms but again It gives the Error that incorrect value for set style. Meaning that it doen’t allow me to define more than one type of atoms and I don’t know
What’s the problem.

have a look at your create_box command and read its documentation
again. that *can* be easily solved by reading the documentation.