Digital BW, The Print

I have a relatively new Epson 1800, which I bought for pure-carbon  
black printing (3 Eboni black cartridges).

Twice now I have had the printer reject (or fail to recognize) an MIS  
refillable cartridge after I refilled and reset it. It was not the  
same cartridge, and both times I got things going again by replacing  
the MIS chip with a chip from one of the original Epson cartridges.

I have not had this kind of failure with MIS chips before (ie ---  
works fine -- reset -- not recognized).  Reseating the cartridges made  
no difference.

Any thoughts??