NETWORKDAYS to Calculate Duration

I need to calculate the duration between two dates. One of which happens to be in the future, however I didn't think that should matter. The screenshot below shows my data, and as you can see I am getting the #Invalid Data Type error, why I don't know why. My Duration column is set to text/number. And the second screenshot shows how my formula is structured. This is super easy to calculate in Excel, so I don't understand what I am doing wrong. I even reviewed the SS web page for this function, and I am still getting this error. Thanks in advance for your assistance.

=NETWORKDAYS([Plan / Develop - Start Date]1, [Plan / Develop - End Date]1)

Sherry Fox

Project Analyst | Core Quality Services (QMS Transformation)


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