in form design view look at the backcolor for a control that has the right colour.
if it is a custom colour it might look something like this
View attachment 122137
1. if it does, copy the value (#66CCFF in this example)
2. if it is a description such as 'access theme 1' or similar, click on the 3 dot caret to the right, click on more colors and select the custom tab. You will see a similar value on the Hex line - copy this value
View attachment 122138
3. Now go to your conditional formatting rule and click the down arrow next to the back color button. This will open the color picker per 2 above, go to the more colors>custom tab and paste your value in the hex box., then click OK job done
Make sure the backstyle is set to normal
an alternative option if 'N/A' represents a null value (i.e. you have used something like nz(myfield,"N/A") then you don't need to use conditional formatting at all, just pass the null value and you can set the control format property to @;[red]"N/A"