Hi @BarryHicks,
Please see the following image:

Click the Photos, then it would allow you to select image to upload. From the error message, it seems the data didn't convert to the right format.
Try to change the formula with the following:
"@{formatDateTime('2016-12-15','yyyy-MM-dd hh:mm:ss')}"
If this still not working, take use of the compose action, then in the inputs, type the formula below:
"@formatDateTime('2016-12-15','yyyy-MM-dd hh:mm:ss')"
After that, use the output from the compose to insert the corresponding rows in SQL server.
Regards