Help Cells in Cell definition in Bex Query

Hi Guys,

I have created a query with cell definition and used 3 help cells. Now I have observed that 3 or 4 times the help cells disappearing from my query definition and error messages in my query like below since now the all the cells where I used these help cells have to be redone. Now my definitons are replaced by something like this.

= DGNM9YRW53859ZOVD0WHP7VW0

'Demand EA' * DGNM9O5T2UDGTY2ML6ZE7H3CG

Could you please tell me what I am doing wrong. How to avoid this. Also is there a simple way of fixing this. Else I have to redo all cells. Also how can I avoid this in the future.

Any help would be highly appreciated.

Thanks a lot.

Formula term DGATX4S5QBKAXPGD8KUS83CJ4 001 DGNM9O5T2UDGTY2ML6ZE7H3CG is not available