Using FF6tools to edit FF5 Advance Dialogue

Sorry to bother all of you again with my apparent stupidity but, I was using FF6tools online to hack the dialogue of FF5 (GBA). To make sure I wouldn't waste a bunch of time, I only changed 2 lines of dialogue before attempting to save and........... it wouldn't let me save because I somehow exceeded memory capacity? I should state, the dialogue I changed I actually made shorter. How does eliminated dialogue take up MORE space? Any insight will be appreciated. For all I know, the true reason it is happening is because I am using Windows 7?