Unable to close document which is in open status with zero balance.
Document was created because some resources/service plans that were used whe the document was created are taxed and others are not. As a result total balance is zero but the tax is not zero.
Such documents can be created as a result of a product bug #PBA-66467.
Please contact your Technical Account Manager of Pooled Technician Associate to and use the bug ID to get further assistance.