I'm using a SETALL() to set the dynamicbackcolor property of all the columns in a grid, but it's not working? What am I missing?

THISFORM.PageFrame1.Page4.grdRextpost.SetAll("DynamicBackColor", ;
"IIF(csrTrans.Posted, RGB(255,0,0, RGB(0,255,0))", "Column")

My backcolor is always white? I thought the above would show Red or green?

Thanks,
Don