Makes sense; my initial guess was wrong. Though I have just tested examples #369 and #390 -- they do return valid data for network printers on the LAN. Does the code return an error message in your tests?

Btw, the code returns different results for the same printer depending on whether the printer name or its network location used. For example:
HP LaserJet 4100 Series PS on MYLAN
\\MYLAN\HPLaserJ