Created Info Area appearing at un-assigned nodes!

Hi SAP Gurus,

I am new to this BW environment and I am learning.

I got the following problem:

My environment is:

Training client: SAP BW 3.1 along with SEM 3.2 and BI content 3.1

What I did is:

I have created an Info area with name ZXX_IA and info objects under this info area. But it is appearing in the unassigned nodes.

My questions are:

1. Why? What went wrong?

2. Can I keep it like that?

3. If it is with unassigned node any problem in future?

Can any body help me in this regard? (my question may be silly to all my seniors...bear with me..)

Thank in advance

Vam C