>>ThisForm.grdInv.SetAll("DynamicBackColor","IIF(threshold<1000,RGB(255,255,0),RGB(255,255,255)","Column")

>A. You're missing a ")" (in bold below)
>B. You may need to refresh the grid a couple times (like in ARCC())
>C. You may want to qualify threshhold with an Alias.

>ThisForm.grdInv.SetAll("DynamicBackColor","IIF(" + alias() + ".threshold<1000, >RGB(255,255,0), RGB(255,255,255))","Column")

Thanks Mike. As I said "dense"! The missing paren took care of it. I'm surprised I did not get an error on that, what would that be? Thanks for the other suggestions too.