Can't call method "Fields" on unblessed reference

##</code><code>##


my $SQLstring = "SELECT * FROM table WHERE field1='";
my $filter = $Request->Form('USERFIELD')->$Item();

# this is taken directly out of the pages of 
# the O'Reilly Book CGI Programming.
# I try to "clean up" the data that was entered 
# by the user and then take that 
# 'untainted data' out of a system variable
#
# the program dosen't work with or without this statement


$filter=~ /^([\w.])$/;
$filter = $1;

$SQLstring .= $filter

my $Provider = "SQLOLEDB";
my $ConnectString = "driver={SQL Server};server=SRVR;database=DB";
my $Conn = $Server->CreateObject("ADODB.Connection");
$Conn->Open($ConnectString);

my $RS = $Conn->Execute( "$SQLstring" );

# this is the line on which the error occurs
while ( ! $RS->{EOF} ) {
	$Response->Write($RS->Fields(0)->{Value});
	$RS->MoveNext;
}
$RS->close;