Prefix and VLAN problems

Hello, I am also having issues with prefixes and the corresponding VLAN tab. Initially, I went through and entered in all of my prefixes, with corresponding VLAN's, net identifications and usage type. However, after I populated the data base with nodes, the prefixes disappear and now when I go to the VLAN tab, all that shows is the net type and VLAN. I cannot edit net identifications. When I go to edit and change the organization and description, none of the changes hold. Any ideas? Thank you William Daly