#3 Double struck characters not shown in MathML

[Mei]

HI,

When I run the transformation of mathml elements using FOP, in AWS Linux, the double struck characters are not displayed. This is the sample of the mathml:

<equation-inline>
    <mathml>
        <math xmlns="http://www.w3.org/1998/Math/MathML">
            <mrow>
                <mi>n</mi>
                <mo>∈</mo>
                <mi>ℕ</mi>
            </mrow>
        </math>
    </mathml>
</equation-inline>

The ℕ character is using unicode U+2115 in my editor. When output to PDF, it was displayed as a slanted N character.
In contrast, if I run on my MacOSX, the N is displayed correctly as double-struck N. The error is only in AWS Linux server. What could have gone wrong? Is double stuck character doesn't work well with Linux?

Please help. Thanks.

Mei