vrops 6.0.2- Manual object releationship mapping disappering after a min

Hi

I am  using vrops 6.0.2  (6.0.2.277062)  and hyperic 5.8.4 with  enterprise license. I am  trying to perform a manual parent child object relationship in vrops.  But the relationship is disappearing  after a min . Can any one guide what could be the issue

Thanks