setting Midi tempo

[Christopher A. LaFond]

Hi,

I am trying to set a Midi tempo of 90 dotted quarter notes per minute. 
According to the Lilypond docs, the correct syntax is:

\midi {     \tempo 4 . = 90 }

However, I keep getting a syntax error (unexpected tempo).  Since it's a 
dotted note, there is supposed to be a space after the "4". I have tried 
all sorts of combinations here of leaving and eliminating the spaces, 
but no luck.

Does anyone know how to resolve this?

Thanks.


--
Chris