Position Assignment in OM

Dear Friends,

Every time and every where I am facing the problem with position assignement. I am not understanding where I am doing mistake. Please help me on this.

The problem is:

I will create a position with back dates and assiging the position with back dates, then in org assignment I am viewing two assignements one is from hiring date and other one from current date.

ex: I have created one position from 01-02-2007 and made that position as vacant from the same day. I have recruited one employee for that position from 01-03-2007. when I am checking the org assigment I have to records like

1st record from 01-03-2007 to 24-03-2007

and 2nd record from 25-03-2007 to 31-12-9999. position showing same.

every time I am facing the same problem.

Why it is delimiting the position and creating new record.

Please explain me if you you.

Kumar