datagridview problem, help

[ckbseng]

i create a datagridview and set the backcolor of the certain cell in the datagridview, it will run normal as the setting i set when run individual form only. but when i put into a panal with using mdiForm. the color of the cell will not able to see at the first time , and i create a button to set the color again then the cells are coloring

so what is the problem actually?
i can run with the color i set and display only in single form
but in mdiform no, for the first time and only display coloring in second time