>OK
>I entered the following code in the grid init:
>

this.SetAll("dynamicbackcolor","iif(left(crgel.Value,1)='S',rgb(125,252,145),rgb(255,255,255))")

>I got a message 'expression is invalid for dynamic backcolor property'!
>What can I do?

The expression seems to be valid 'syntactically'. However does crgel.value evaluate to a string? IOW what does happen if you put in init (comment your setall()):

select (this.recordsource)
messagebox(crgel.value)

Cetin