I see the board that you are using has the below SATA Ports as per the Board's Spec
- 4 x SATA3 6.0 Gb/s Connectors, support RAID (RAID 0, RAID 1 and RAID 10), NCQ, AHCI and Hot Plug*
- 2 x SATA3 6.0 Gb/s Connectors by ASMedia ASM1061, support NCQ, AHCI and Hot Plug*
The reason StoreMI doesn't allow to choose HDD could be because it is connected to one of the "- 2 x SATA3 6.0 Gb/s Connectors by ASMedia ASM1061, support NCQ, AHCI and Hot Plug*" ports which is not support by StoreMI.
All you need to do is change the SATA cable to connect to one of the "- 4 x SATA3 6.0 Gb/s Connectors, support RAID (RAID 0, RAID 1 and RAID 10), NCQ, AHCI and Hot Plug*" port and try StoreMI again. In this case the HDD should be accessible and eligible.