Just wondering if I was doing something wrong with the game because I can only build on ssd. If I build the eclipse I can't build the vengence etc.

Check your Supply Units (SU). While in the game press " i " to check to see how many ships you can build in a certain class. The " i " button essentially opens up the information on how many of each ship you can build. This is similar to "Food" in the Warcraft series by Blizzard. However, you cannot build more farms to increase your supply. To increase your Supply Units, you can change the game settings at the screen where you pick teams, map, etcetera.

 

Hope this helps.