48 x 96" in Illustrator prints short 1.25".

[Navigator7]

I mount my signs of 4x8' dibond or signboard.  
Hence, I set up my artboard to 4x8' and I draw my artwork inside of that.
Many times I've come up short before but today, this error might cost me over $1000.00.
I'm printing vinyl on a Roland SG 540 four color.
How do I trouble shoot this?

[Navigator7]

Above didn't print all my text.  A 4 x 8' square comes out 1.25" shy on length and roughly 1/2" on width.  

[jdanek]

Have you been able to setup your page size?  If so, use the page tool to align the page to the edges of your artboard.  If you have "Show Page Tiling" deselected, then page setup may not be showing up ( so set Show Page Tiling > Show ).  I always set a transparent ( no fill / no stroke ) rectangle to the artboard and lock it.  This forces the RIP / Print Driver to print the entire file and not just the contents which could get clipped.  In Page Setup, choose borderless and align that to your artboard. 

[Navigator7]

Thank you for the reply.  
I center my artwork with the alignment tools.
I will check Page >Tiling >Show
.... 3 minutes later....
I scaled my work 4" high by 8" wide, then changed the setting in my printer to 48 x 96.
The print is beautiful...just the wrong size.  
Is this method wrong?
The blue rectangle has no stroke only fill.
"I always set a transparent ( no fill / no stroke ) rectangle to the artboard and lock it.  This forces the RIP / Print Driver to print the entire file and not just the contents which could get clipped."
I will take you suggestions to the shop next time I print!