Hi
Perhaps to expand on what Aleksandar said:
The planning worksheet is not like other worksheets where each batch is completely separate, with the planning worksheet the system looks at what is in the other batches when it is calculating so that message means that the system found items, that would have been calculated now, in another batch and therefore wont be calculating them
The reason what it does this is so that you have have raw materials in one batch and finished goods in another and they all talk together
If you don't need to do this then your safest bet is always to keep the batches empty when calculating (I normally delete the other batches and only have one, then there is no other batched that might have old stuff in them)
Cheers
Nev