Problem importing plan in p3e with calendars

I have imported a contractor plan into our p3e database (v5) and just as a test, i baselined it and then scheduled it(not changing the data date.

only to find that a significant number of activities had changed date.

 

The fisrt thing i noticed was that an activity with a 7 day calendar assigned was being treated as if th calender was a 5 day working week.

 

I suspect this is what is occuring on most of the other

 

any advice?