Planning Object Structure not getting saved.

HI,

I had deactivated the PA and then the POS. I had included a new chara and then when I try to save, it gives the following message.

Planning object structure ABCD not saved

Message no. /SAPAPO/TSM173

I had done the same steps for other POS and it had worked correctly. but for this getting a strange error.

Can someone help me out in this....

Thanks

Aswath.