missing data while exporting-importing

If you have a resource assigned to the same activity multiple times, when you import the XER it only recognises the first assignment and therfore missess any others. Consequently the manhours when imported will be less.

Several companies i have done work for only allow planners to assign a resource once to an activity for this very reason. On the resources tab when in the Project screen, there is a tick box in the bottom right to toggle the ability to assign multiple resources.

But how you solve the issue when you need to use the same resource on the same activity but on different shifts.

Say 10 carpenters from Monday to Friday while 20 carpenters on Saturdays because on Saturdays they will be available to work on the activity while during the regular week they will work on other activities? Of course there are many other reasons you might have to recur to multiple assignments. It might be than on same shift some of the same resource work full time while others work half time on the activity and the rest of the day on other activities. This type of assignments happen every day. 

Oliver,

in that project I have not assigned the same resource more than once in the same activity (no shifts) and I checked also the box in the bottom right and it is ticked "Resources can be assigned to the same activity more than once''.

regards

try this, go to edit>user preferences>resource analysis and SELECT "Preserve the unit, duration and unit/time for existing assigments" and try to reimport the datas again.