Is The Backdrop Turned On? If so the text is not displayed unless you call it during a loop... If you have any 3D objects or have had any, you have to use the command "Backdrop Off"... If you want to keep the Backdrop on then you must tell the computer to display the text every time the screen refreshes.
Sync On
Do
Center Text 320,240,"Your Text Here"
If Spacekey()=1 then exit
Sync
Loop
Well... I hope that helps...(Is it just me or do I say "Well... I hope that helps" alot?)
Do not thwart the way of the dragon. For thou tasteth like chicken.