I haven't used a 4000 in several years, but will try to help...
The 4000 has both MK and PK carts, and uses each depending on the Media Type setting selected when printing. I believe you can do an alignment in MK or PK mode, and don't recall a paper selection in the adjustment menu.... are you doing the alignment thru the Epson utilities on your computer, or directly from the printer's control panel?
So, you have Matte Black ink in the MK channel and PiezoFlush in the other seven channels, or you have PiezoFlush in all 8 channels? Does your printer print anything, or give the error before printing the alignment pattern?