Hello,
 
I'm having 
difficulty with the trees. This is what I have so far: The items in bold is what 
I can't get. Any help will be appreciated.
  - Geotel Engineering 
  Document 125
 
  
    - Base 
    Header
 
    
      - Length 
      10
 
      - Type: 
      SERVICE_CONTROL
 
      
        - Header         
        // for SERVICE_CONTROL
 
        
ged125_item = proto_tree_add_item(tree, 
proto_ged125, tvb, 0, -1, TRUE); // 
displays the protocol name ("Geotel Engineering Document") on the tree 
ged125_tree = 
proto_item_add_subtree(ged125_item, ett_ged125); // doesn't display anything further, must set up something
ged125_sub_item = proto_tree_add_item( 
ged125_tree, hf_ged125_header, tvb, offset, 8, TRUE ); // 
makes the "base header" tree
ged125_header_tree = 
proto_item_add_subtree(ged125_sub_item, ett_ged125);
length = tvb_get_ntohl(tvb, offset) + 
EIGHT_BYTES; // first 4 bytes of 
header gives entire ged125 packet size but it's always 8 bytes off so I add it 
here
proto_tree_add_uint(ged125_header_tree, 
hf_ged125_length, tvb, offset, 4, length);
offset+=4; //We increment the offset to get past the 4 bytes indicating 
length
type = tvb_get_ntohl(tvb, offset);
proto_tree_add_uint(ged125_header_tree, 
hf_ged125_type, tvb, offset, 4, type); // add the 
message "Type" to the 
header tree
-Martin