Problem in format of data file while using atom_style full

I am trying to create a lmp file for CNT enbedded Al-Si alloy. I am using the atom_style full. LAMMPS is reading the file for CNT properly. But when I am trying to incorporate the data file for Al-Si alloy using the following lines:
region 1 cylinder z 0.0 0.0 5.42 0 100
group 1 region 1
read_data AlSialloy.alloy add append group 1
LAMMPS is showing the error:
Invalid atom type in masses section of data file: 2 28.085
It is not taking the second atom type (Si).
Kindly suggest me how to modify the data file for AlSialloy so that LAMMPS will consider the second type atom in the file. I am attaching the AlSialloy file.
AlSialloy.alloy (562.0 KB)

Kindly study the documentation of the read_data command and specifically the parts about limitations when using the append option and about the “extra” and “offset” options. It is all explained there.

Thank you very much for the suggestion.