Excel Formula Error

[johnhopkin1997]

Hello, i've been struggling with this problem for a week now.

I inserted a formula in a cell, it worked just fine for only a certain condition (the month January), but it didn't work with other months. And i think there's nothing wrong with the formula or the resource data, so what's wrong with my worksheet? Thank you for your help.

it works in januaryerrors with other months

[#2]

If you step through your formula, which part of the formula returns the #N/A ? Is it the MATCH? Very hard to troubleshoot without the actual file.

[#3]

In formula DATA(year, month, day) you input month=selected_period
How did you define selected_period?