The spelling mistake was in the message, not in the program.
any way, I discoverd that property 'DynamicBackColor' available only in the column, not in the text.
my problems is:
1. My question was how can I change one cell, not all the column.
2. when I run this command

ThisForm.Grid1.Column2.DynamicBackColor=rgb(125,112,23)

I get a essage 'Data type is invalid for this property'.
Help, please!