Aniya:
There can be two reasons for this anomaly:
1) some candidates do not list all the occupational groups in the preference form. In 2010, Junaid khan ( merit no 20) had given only one preference: DMG. But he wasn't allocated because DMG slots were take by those who were above him in the merit list. He could have been easily allocated in PsP, FSP or any other group only if he had mentioned any other group besides DmG on the preference form. So, this is first case scenario.
2) suitability clause.
The commission do not deem you fit for a particular group. In 2007, there were more than 20 victims of this clause. But, it's mostly applied to DMG, PSP and FSP. But in general, one can be considered unfit for any group.

In KP, the lady on merit no22( KP ) is allocated to OMG and another lady on merit no 40( KP) is allocated to PAAS. She is the last one who got allocated. So 16 candidates between merit no 22 and merit no 40 have not been allocated.
And, merit no 40( KP) is not allocated on women or minorities quota.