Asp/ado/xp_sendmail/return Codes

I have a stored procedure that builds and sends an email using xp_sendmail. It is called after the user makes a change to a form (it tells the support centre that a change has occurred.)

The last bit of my SP is this:
-- It fails if it has no recipient list
if isnull(@recip, '') = '' set @recip = @supportemail

declare @rc int -- have also tried changing it to bit

exec @rc = master..xp_sendmail
@recipients = @supportemail
, @message = @msg
, @subject = @subj
, @no_output = 'False'
, @query = @q
, @width = 200

/*
Return Code Values
0 (success) or 1 (failure)
*/

select @rc
return @rc
If I call it through query analyzer, @rc is 0 and I receive the email.
If I call it through my ASP page (which worked earlier), cint(rs.fields(0)) is -1 and I do not get the email.

strSQL = "exec pr_EmailNotification " & iRequestID
writeline "<P>" & strSQL

set rs = ConnObj.Execute (strSQL)
writeline "<P> Result: " & cint(rs.fields(0)) '0 (success) or 1 (failure)

(All variables are declared.)

It was working earlier, I had proven it... I thought it was the return @rc line that was doing it and was just keeping in select @rc for debugging. When I was ready to move on, I removed my debug statement, and then it started failing. I've put it back in, but it still fails, so I must have also removed something else, or changed something, or something.

I'm at wits end. It still works perfectly through Query Analyzer. But not ASP.