FYI - you can use Debug.Print to put the results of something in the immediate window (available under the View menu)
Debug.Print sConnection

Or you can hover over a variable (not as useful, when it's this long) when stepping through

Or you can type:
?sConnection
in the immediate window, and see what it is when stepping through the code.

I get your connection string as this...
Provider=Microsoft.ACE.OLEDB.12.0;User ID=Admin;Data Source=H:\Jonathon Hunter Hill\Mail Merge\AirMaster V 0.9.xlsm;Mode=Read;Extended Properties="HDR=YES;IMEX=1;";Jet OLEDB:System database="";Jet OLEDB:Registry Path="";Jet OLEDB:Engine Type=35;Jet OLEDB:

I'm no expert, but that doesn't look wrong around the "Extended Properties" area...