Stacked Switches no link light

Hi,

I have a stack of 10 Dell N2048 Switches.  9x standard N2048 and 1x N2048P.  They are all stacked and everything is working.  However there is a linked cable between the top switch and the bottom switch which doesn't appear to have a link light.  The cables going from one switch to the other are all ok, the numbers are all correct and all seems to be working.  I have looked at another stack and there is a link light between the top and bottom switches.  Is this normal or something that needs to be looked at in case the stack needs to be maintained or rebooted?

I have attached pictures.

Thanks in advance.

StackBottom SwitchTop Switch