Help Fill Series

[Mark]

Hello, Any help appreciated,

I created a sheet a few days ago and added a formula the dragged the formula down the sheet. All good so far the Fill series worked fine.

Ive now come back to the sheet and I'm trying to extend the formula down another 30 cells and it won't allow me to fill series??

Ive tried copy & Pasting it, Dragging it. CRTL Drag and the Fill series option is greyed out?

Any Ideas anyone Please.

Thanks
This is the formula i'm dragging the 1555 is the reference that should increment.

=INDIRECT(ADDRESS(1555,($EM$4*7)))

 

[XLPadawan]

Mark, If you're still alive and kicking, would you mind uploading the sheet? I'll await your response from my cryogenic chamber. I've set it to wake me in 2019.