selecting audio inputs from standalones in os x 10.5

d.'s icon

I am testing a standalone app made with max 5 and os x 10.4 on a 10.5 imac. I cannot get audio to use the line in exclusively. It always comes through the built in mic as well. Os settings are on "line in." DSP says Input device "line in" but input source says "built in mic" full time with no other options.

Do I need to upgrade to os x 5 in order to develop for it or is the problem something else?

Thanks.

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D.