HP Officejet 7500a - Cant print A3

Hi,

I recently purchased a HP OfficeJet 7500a, I would like to print a spreadsheet in Excel 2007 in A3...

When the printer is turned off, the option in Excel to print in A3 is available. Allowing me to create the spreadsheet around those margins. However, once the printer is connected (wirelessly) the A3 option disappears. All drivers are up to date and I dont see why this is happening.

Can anyone help me? 

Thanks