creating material in material.exe

Hello,
I would like to create a scatter tables for a mixture of two materials and I try to figure out how option "Enter fraction by weight of each element" works in program material.exe of Penelope Code?

We have for example one material – Alanine (C6H7NO2) fraction by weight can get from http://physics.nist.gov/cgi-bin/Star/compos.pl?105. When i use option “Enter chemical formula” I get the same scattering tables as for predefined Alanine material in pdcompose.p08 data bank. But when I put fraction by weight: 0.079190 H, 0.404439 C, 0.157213 N, 0.359159 I get incorrect number of atoms: H – 1, C – 0.4, N – 0.1, O – 0.3 (should be H – 7, C – 3, N – 1, O – 2)
Maybe someone know what I`m doing wrong using fraction by weight of each element ?