Blank cell value when setValue before a tab

Hello guys. I hope one of you can help me with this one.

When I set a cell value using the setValue() method it works perfectly :sunglasses: , the cell acquires the value that I want it to have, but then when I leave the cell to move upon to the next USING TAB on my keyboard the value that I had set just dissapears! :confused: How can I preserve the value?