I defined a few functions in a workbook using VBA, and then expected to be able to use them in a cell formula - but Excel does not recognise the function. I just get #NAME?<
Activate macros.
I think there might be a problem if your Module has the same name as your function. Try renaming your module or your function.
I had an identical problem, including a working function that later stopped working giving a #NAME error. I have managed to fix both by making sure the name of the module is not the same as the name of the function. I had a working function F_1 in Module1, I changed the module name to F_1 and it stopped working, now back at Module1 and the function works again. My second function also began working when I changed the module name from F_2 to Module2.