Problem in maintaining relationships in scheduling project dates

Dear all,

My project is having 1000 activities.Different WBS has different dates.First the dates were maintained manually.But then after having meeting.

Management needed the scheduling according to time taken for an activity.

While maintaining relationships between all i.e SS and FS.There is some problem in relationship in some activities.

Like 1sts activity date is maintained, but in my project error arises in relationship of first activity with associated activities.ie activity 10 with 20 and 30.

There are some problem in between some of the projects also.like activity 80 ,90 etc

This is creating a major hindrence please help.

I carry out schedule from edit >dates>shedule ctrl+f9

Cheers