Another option is to transfer the data via excel. Both programs can be exported or copied into excel. It's viewed as the nuts and bolts approach but it works.
Copy MSProj. data and paste it into a spreadsheet.
Export Primavera data into a spreadsheet.
Now just copy and paste data from one spreadsheet into the other as long as the data columns match....such as early start dates, activity description, activity ID.....
hope this helps,