multiple js files (call function to each other)

I am having trouble calling a function that lies within a second js file. I am sure that I am just not calling it correctly or I need to reference it like I do on the html page. Could someone give me the correct syntax please. Its inside a catch statement but if the function is on that page it works so I don’t think that is it.

Thanks in advance.

[CODE]
function ZoomToLevel(iLevel) {
try
{
m_mapViewer.setLevel(iLevel);
//Request a new map.
submit();
}
catch(errorObject)
{
// This is the name of the function that resides in a file called error.js
HandleErrors2();
}
}

[/CODE]

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