Here's the low-down on Slingbox passwords (I'm referring to Slingbox hardware password, not a Sling website password):
Your Slingbox has two passwords: User and Admin.
Both allow you to watch. User only allows you to watch. Admin allows you to watch and configure.
Slingbox can only accommodate one connection at a time. If someone is already connected and watching, User will get a busy message. Admin will get a busy message with the option of terminating the current connection so it can watch/configure. Admin's "kick to connect" ability is always available, even if the current person used Admin. In short, two people who know the Admin password can take turns kicking each other and fight over the Slingbox- so don't share your Admin password.
The admin password slider is how you tell the Slingbox which password you're sending. If you send a valid User PW with admin slider ON, it'll fail. If you send a valid Admin PW with the slider OFF, it'll fail. In short, User PW = slider OFF; Admin PW = slider ON.
If you still have problems, delete/re-add the Slingbox entry in the directory. Last resort would be to delete the directory entry AND do a hard reset on the Slingbox... basically start over.
Good luck !
I had the same problem with my new Echostar HDS-600RS. Turns out I have an apple aiport extreme which doesn't support UPNP. This allows the sling box to connect to the internet by configuring your NAT on the router. Instead, I had to :
1. Assign a static ip address on the aiport extreme so that everytime it boots up it gets the same local address. Eg 10.0.x.x or 192.168.x.x
2. Setup port forwarding for my sling box on por 5001 on UDP and TCP agaisnt the ip address given in step 1.
3. Reboot the Echostar box.
4. Connect using my IPad app.
For some reason even though the ipad is on the same network it has to go out to the internet and back again in order to connect to your slim box.
Anyways, once I had done the above it works fine now inside my home network and out and about on 3g.