Combine cells using CONCATENATE Excel

Basically step by step it's:
1- To combine the contents of several cells, you select the range to concatenate and configure the following settings:
2- Cells into one under "What to merge";
3- Select the delimiter you want under "Separate values with", it's a comma and a space in this example;
4- Choose where you want to place the result, and most importantly.

[StephenBeale]

*However, * if I type in the cells manually, it still doesn't work i.e. =CONCATENATE(E2, F2)
*Any thoughts?*
Thanks!