html page uploading file to ashx page

I think i nearly have it here but i just get grab the file correctly.

I Have

Dim CVFile As HttpPostedFile = Request.Files("datafile")

Which i *Hope* grabs the datafile input file with type="file" and set it to CVFILE which i *think* should be httppostedfile
Then i want to save it in same directory under the name steve.pdf

CVFile.SaveAs("steve.pdf")

But i am getting "Object reference not set to an instance of an object" on second line.

Any ideas? ...