Excel 2016 won't copy a formula down the column

On every formula I have attempted to copy down the column excel continues to return the value received in the first row. As an example I need to reformat a date field (e.g., 20130422 to 04/22/2013). I used the left, mid and right formulas that did in fact return the correct answer but when I proceeded to copy the formula down the column i received the following results in every subsequent row in the columns I copied the formula down in:

2013 30 22
2013 30 22
2013 30 22
2013 30 22
2013 30 22

Additionally, I incurred similar results on all the formulas I attempted to implement in the worksheet whereby the formula maintained the same result as it returned in the first row for all subsequent rows regardless of the formula type. The worksheet somehow appears to be limiting my modifications.

Any clues?

Thank you that did it. Greatly appreciated