Unfortunately there is a problem with the goniometer on DaVinci1, meaning that there will be a slight shift of the peaks (it is different for different angles) compared to the database.
(Still working on it! Sorry for the delay.)
After importing your data, you need to edit the following fields under "Corrections"
These values have been found by fitting both the measurements of NIST 660a (LaB6) and NIST 1967a (corundum) standards simultaneously.
Example: How to refine for a LaB6 sample (coated on Si-wafer). Keep Zero error fixed at "-0.1042", whilst refine the sample height.
Figures illustrating the offsets can be found here.