If you belong to multiple user groups, which are controlled by different fairshare policies, each group probably has a different dynamic share priority at any given time. By default, if any one of these groups becomes the highest priority user, you could be the highest priority user in that group, and LSF would attempt to place your job.
To restrict the number of fairshare policies that will affect your job, submit your job and specify a single user group that your job will belong to, for the purposes of fairshare scheduling. LSF will not attempt to dispatch this job unless the group you specified is the highest priority user. If you become the highest priority user because of some other share assignment, another one of your jobs might be dispatched, but not this one.