Can't use echo when debugging hacks?

[WetWired]

I've noticed that if I try to use echo to output debug information for a hack that I'm writing that every page that passes that point will return a blank page (without the echoed content) unless I follow the echo line with an exit. Why does it do this and how can I stop it?

[Paul M]

Dunno, I use echo all the while when debugging, it occasion fails (on vb error messages) but works 95% of the time.