Formulae not working as they should

17-08-2015 AM.xlsx

I created the excel worksheet above to work in conjunction with an app I have on my phone to collect data. The app is a tally counter that simply records the time of every action counted, and emails it to me. I import that data as text into the above worksheet (as I already have done on the sheets "Robot 2" & "Robot 3") and it (in theory) uses a simply "Countif" function to count the number of times each action occurred.

However, as can be seen in the sheet this function is faulting, and not counting anything, seemingly at random. For example, on sheet "Robot 2" there were three successful actions at 10:22 (C23;C25), yet the cell that should be counting these (W12) counts none, even though the cells above and below that one are working fine.

As I'm sure you can see this error happens very frequently, and I cannot seem to resolve it, by retyping the data in manually or refreshing the formulae.

Does anyone know why this is occurring? Without these sheets working correctly I'm really going to struggle to move forward with my work.

Thanks,
Joe R.

EDIT: I have just been messing around with this some more and found that changing the column with the reference times, V, seems to affect the formula's ability to count, it is, however, very unreliable. Why is it working like this? How do I fix it?