Calc will not show SUM values in cell, only formulas.

LO Calc, on a Windows 8.0 ASUS laptop. When using the SUM function and selecting the cells to add, the formula stays in the cell and will not display the value [shows =SUM(C5-C4) instead of 1.2]. Tools/Options/Libre Calc/ View/Display the Formulas check-box is unchecked. This was happening before I just updated to the version of LibreOffice.

Do all the other cells containing formulae display the results?
What is the ‘Numbers’ format code of a cell showing the issue?
(For what reason do you use the SUM function instead of simply =C5-C4 to just calculate the difference? )

Sounds like the cell containing the formula is formatted as text. Changing it to number after the formula is entered seemingly will not work as the data (the formula) is already text. Try changing the format to number and re-entering the formula