Quartus Programmer 209066 Error

Hi All, I am having trouble programming a flash device attached to an Altera EP4SGX180. The flash device is EPCS128. The chain contains 3 devices in total. 2 of these are unknown so I have named/set their IR lengths. However, when I try to start programming I receive the following error: Error (209066): The instruction register length for the EP4SGX180 device at position 1 in the JTAG chain is unknown.

With this being an my known Altera device I am unable to set this. Does anyone have any ideas what I am doing wrong? Thanks