iMA vs MA in Indicators list

[billr]

I've got this in my code for a Custom Indicator: iMA(NULL,0,45,0,2,5,0);

When I drop the Moving Average indicator from the regular Indicators folder, and set the parameters to what I think should be to duplicate it (45 periods, smoothed, and typical: see attached picture) the lines are not equal. Can anyone tell me why?

Thanks in advance