Excel help on flagging date and not flagging blank cells

I have a spreadsheet that I have created and I need the dates entered to flag red if they are less than or equal to 30 days from today's date. I entered the conditional cell value of =TODAY()+30 and it flags red like I need it to. The problem now is that all cells in that column that are blank flag red. I would like them to stay the original color when blank. I have attached the file. The column is called "Release Date". Any help would be much appreciated, thanks in advance.