custom disk partition with diskpart problem

I am trying to customize the disk layout in my Windows 8.1 TS. What I did was add a command line TS with diskpart and disable the default Format and Partition Disk task. I know the diskpart (with script) command worked as expect as I tested it in my testing box first. When I boot up the lite touch media and select the windows 8.1 TS, MDT failed at the inject driver stage (with using the customized diskpart script). But it is working fine if I use the default format and partition disk task.Can someone advice how I can troubleshoot this problem?

Thanks