
Check the size / available space on the target volume during deployment. I would guess that the space you have allocated is not enough for the WIM to be downloaded and also unpacked (we had a similar issue).
The logic being used by RCA for determining the initial deployment partition is somewhat flawed in my opinion (especially relevant for FAT images). If this is the case ask support for HOTFIX_OVCM_OSMGR_V9.1_2015-11-02_1446456475085baa5.zip - this has an updated Payload which creates larger partition sizes.