“Posting only possible in periods 2008/10 and 2008/09 in company code…”.
This is a typical error when you are working in a test environment. This will be job controlled in a production environment and should never be an issue there. It means that the fiscal period (the previous month) is not closed yet. You are probably trying to post a goods movement in the new fiscal period/month. The system will not stand for this kind of behavior! First you have to close the previous period. You can use transaction MMPV – Close Period for Material Master Records to close the previous period.
When you are in a test environment you don’t really care about checks and balances: tick the button Close period only. This will get SAP into the new period without any problems.
And to check the current period for your company use OMSY. This will help you determine what the next period is to fill out in MMPV. Your Finance colleagues can tell you what the current fiscal period is. Usually the periods follow the calendar month logic. It is also possible that the fiscal year is determined otherwise.
Especially in test environments that are hardly ever used periods may not have been closed for months. In this case you have to close each period one-by-one.