Try insert header

Check.pm

@@ -250,7 +250,9 @@ EOF
     my $DUmaxTime      = timeStamp2($Info{DUDailyMaxTime});
     my $DUInodemaxTime = timeStamp2($Info{DUInodeDailyMaxTime});
 
-    my $content = eval ("<p>Header content here</p>");
+    my $content = eval ("qq{
+      <p>Header content here</p>
+    }");
 
     Header("BackupPC: Check", $content);
     Trailer();