Log Checkbox with Tablet

I have a checklist that we fill out using tablets.  I made a checkbox and a text field with a rule that if the checkbox is checked the textbox would fill in with the user, date, time.  It worked great on the computer, but when I went out to the floor, it is not logging the information.  It seems that it does not work with the mobile devices.  
Is there any way around this?  I like how I have set it up, but I have to be able to log who checked the box and when.

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Sarah Burres
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