Conditional formatting does not work Please help

3 columns below - D, E, and F

Orig spreadsheet just had Issue Date and Response Deadline. I have been asked to make Response Deadline turn the cell Red or Green depending on whether the date in Response Deadline is more than 10 days after Issue Date, ie day 11 onwards is Red. So, I added the middle column which calculates the number of days between the issue date and the response (received!!). I am going to 'hide' the middle column when it's done. I have tried everything I can to make the cells in column F turn Red or Green but I don't seem to be getting a proper menu for my conditional formatting.
Please see attached.

Don't use the IF, just $E$2>10

But make sure that each cell has its own formula (i.e. referring to E3,E4 etc), as otherwise it all considers $E$2 regardless of the actual cell.

Dip11! But it only works in Column "E". I would like Column "F" to be highlighted if the value in Column E is greater than 10. Please help me