Be careful relying on colour - as has been said many times before you have to cater for colour blind users.

The physical space and instructions might be enough (though a screen shot would help). You could also look at using bold text or perhaps a border to help differentiate this row from the others.

Are you getting feedback that people don't know what to do?

**UPDATE**

Based on the screen shot other things that spring to mind are:

* Increase the size of that row
* Use brighter colours (rather than just different colours)
* Use of tooltips perhaps.

You might find you have to do a combination of these things rather than there being one change that makes the difference.