Packing NuGet projects compiled in release mode

Is there some way to make a NuGet package using code compiled in release mode? Or is there some reason I should only publish (make available locally, in this case) packages compiled in debug mode?

Every time I call nuget pack from my project directory, where I have the nuspec file below, on code I have only compiled in release mode, it complains about not finding the DLL in the debug folder ("\bin\Debug\SomeProject.dll"). If I compile it in debug mode, those files are there and it packs them up as it should.

<?xml version="1.0"?>
<package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
    <metadata>
        <id>$id$</id>
        <version>$version$</version>
        <authors>$author$</authors>
        <owners>$author$</owners>
        <iconUrl>http://somewhere/project.png</iconUrl>
        <requireLicenseAcceptance>false</requireLicenseAcceptance>
        <description>$description$</description>
    </metadata>
</package>