Business Partner number not assigned to ORG unit

hello colleagues,

I cretaed an Org Unit at the highest level, i have assigned Basic data, address data and i have assigned function and attribute, but when i save the Org unit,I am not getting the BP number,

can anyone tell me what could be reaosn for this, but normally whenever a new org unit is created

a BP has to be assigned to it right

please help me with this problem

regards

chandu