first, this is the EDA, not the UDA 
but that's ok, the UDA is a great appliance too.
but that IP address is the address you gave your EDA, or at least it should be. if it's not, try adding a new esx server. this will generate a new pxe-boot config where the ip is filled in.
if it still won't read the netstg2.img, try importing the pxe files from the CD with the link on the main page. could be the built-in pxeboot files are for a slightly differnet version of esx than the one you're using.