KM01153491 In case it helps...
Problem
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A DP 7.03 VMware backup fails...
[Warning] From: VEPALIB_VMWARE@blah003.group.net "/FRX" Time: 8/26/2014 7:03:14 PM
Virtual Machine 'BLAH01': Could not find valid previous backup ...
[Warning] From: VEPALIB_VMWARE@blah003.group.net "/FRX" Time: 8/26/2014 7:03:14 PM
[172:151] Virtual machine 'BLAH01': Incremental/Differential backup not enabled.
Solution
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This problem is resolved in SSPNT700_034.
The code from SSPNT700_034 should be installed on the ESX server.
Contact HP support and request SSPNT700_034.