First a few things to try, at what temperature is it in your monitors enclosure?
They require it to be fairly hot, basking spot should be at 130 degrees. Cold savs get sick real fast.
What substrate are you using? Fine substrates like coconut hair or wood shavings can become ingested with the cricket and choke the lizard.
Your water bowl needs to be big enough to swim in, and always have fresh clean water.
Shy away from using a fish tank with a screen cover, it will allow all the humidity to rise out, and become dry and arid in there.
Go to the pro-exotics web site, links are everywhere. They have tons of great SAV info, and a couple books (get the books) and they sell a temperature gun so you can measure your temps.
Warm that baby up, and give him a swim, it may come around.
do you have a reptile vet close by?
Good luck,
Regards,
Wayne A. Harvey

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1.0.0 Ball Python - Python regius "Cane" Rescue
1.2.9 Storeria dekayi Casper, Xena, Athena, & Kids
0.0.2 Thamnophis marcianus - Checkered Garters "spot" & "Zig"
0.0.1 Thamnophis sirtalis - eastern Garter - Princess
1.0.0 Thamnophis pickeringi - Puget Sound Garter "Sky" (adult, Sky blue)
0.0.1 Nerodia sipedon - Water Snake - "Aqua"
0.1.10 Storeria occipitomaculata - Red Belly snakes
0.0.1 Amelanistic Corn Snake "CY" Juvinile CB
0.1.0. Pueblan Milk snake "Oreo" adult CB
1.0.0. ASIAN GREEN SNAKE 3' WC Cyclophiops major
0.0.1. Savannah Monitor "CHOMPER"
0.1.0. Green Anole "Crystal" WC
1.0.0. K9 "ACE" Black Cockapoo
0.2.0. Feline"Felix"(R.I.P. 4/27/08) "Kaja" & "Silver"
0.1.0. calico RAT
2.4.?? Mice - Feeder farm - Crickets / fish
More herps than I could ever list out back on the land. 
