Commission is something seem easy, yet never easy. What make it difficult is not the calculation method itself, but more into how and when the readily calculated commission can be released too sales people. For example, some company may says, OK, we have SO we have Invoice, commission is calculated, but to release it, the invoice must has been paid first. Some says, not enough, the money must be in the bank too. Some says, need the be paid on time and the selling price must not too low, etc...and guess what, it could be more complex than this especially when deal with SMEs.
In some case, you may found a weird Access Denied (Document type: Users, Operation: read) after deep system upgrade. While checking the setting for that user, it seem all correct. Here is the fix.
ithholding Tax is a required feature if you do business in Thailand (and as I know in many other part of the world), yet I found it not available in many standard ERP packages. Ecosoft has developed an extension to accounting module which will make it comply with Thai Withholding Tax rule and is now freely available at http://apps.openerp.com (search for account_thai_wht).