Mathcad New license trouble

Hi ...

Well, this is why I hate computers for a simple Maths course ... anyway ...

Need a new license for Mathcad ... filled out the form ... get to volume serial number and nothing! Follow the instructions ... and when I put in 'vol c' I get a message telling me "The system cannot find the drive specified"

I've tried several different ways (capitals/little letters, different drive letters ...) nope ... not one thing works!

Any idea?