DriveOne couldn't open Password protected excel Files on iPhone

I started using OneDrive on my Laptop (win7) and iPhone (5S, iOS 8.1.2) after long time of using DropBox. For my surprise, OneDrive on my iPhone can't open password protected Excel Files. I got "The operation couldn't be completed. OfficeImportErrorDomain error 912". So, why DropBox Could and OneDrive couldn't?

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