If XMLA script isn't working you could try SSIS using AMO to backup the databases. We backup ours twice a day to catch any deployments........
Sometimes you have to just use what works.
Jonathan Butler (7/17/2008)
Here's VB Net Script to do the same using AMO....in SSISVariables are declared at Package level and are configured using Package configurations (XML files).
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Pragmatism is a disease that gets things done.