Microserver Gen8 unattended Installation fails at disk partitioning

[sipsip]

Hello all

I try to configure an unattended installation of Windows Server 2012 Essentials R2 on HP MicroServer Gen8.

I created an unattendend.xml and it works... but only with one partition, as soon as i add more partition it fails.

Maybe someone of you can help me...

here my disk configuration:

<DiskConfiguration>
                <WillShowUI>OnError</WillShowUI>
                <Disk wcm:action="add">
                    <CreatePartitions>
                        <CreatePartition wcm:action="add">
                            <Order>1</Order>
                            <Size>350</Size>
                            <Type>Primary</Type>
                        </CreatePartition>
                        <CreatePartition wcm:action="add">
                            <Order>2</Order>
                            <Type>Primary</Type>
                            <Size>100000</Size>
                            <Extend>true</Extend>
                        </CreatePartition>
                    </CreatePartitions>
                    <ModifyPartitions>
                        <ModifyPartition wcm:action="add">
                            <Active>true</Active>
                            <Format>NTFS</Format>
                            <Label>boot</Label>
                            <Order>1</Order>
                            <PartitionID>1</PartitionID>
                        </ModifyPartition>
                        <ModifyPartition wcm:action="add">
                            <Order>2</Order>
                            <PartitionID>2</PartitionID>
                            <Label>system</Label>
                            <Format>NTFS</Format>
                        </ModifyPartition>
                    </ModifyPartitions>
                    <DiskID>0</DiskID>
                    <WillWipeDisk>true</WillWipeDisk>
                </Disk>
                <Disk wcm:action="add">
                    <CreatePartitions>
                        <CreatePartition wcm:action="add">
                            <Order>1</Order>
                            <Size>100000</Size>
                            <Type>Primary</Type>
                        </CreatePartition>
                    </CreatePartitions>
                    <ModifyPartitions>
                        <ModifyPartition wcm:action="add">
                            <Active>true</Active>
                            <Extend>true</Extend>
                            <Format>NTFS</Format>
                            <Letter>E</Letter>
                            <Order>1</Order>
                            <PartitionID>1</PartitionID>
                        </ModifyPartition>
                    </ModifyPartitions>
                    <DiskID>1</DiskID>
                    <WillWipeDisk>true</WillWipeDisk>
                </Disk>
            </DiskConfiguration>

 regards