Cannot format

[nocstaff@urbancom.net]

I made a custom entity called total job time, and I tried to make an entity based report template that includes this. However, it calculates in the report as seconds. I tried to adding formation coding in the html like

<strong>Total Job Time:</strong> {{duration\format(duration)}}

and I also tried to calculate it within the html and produce that output like here

<tr>
<td style="width:50%;">
<strong>Completion Time:</strong> {{dateEnd}}
</td>
<td style="width:50%;">
<strong>Total Job Time:</strong> {{duration\format(duration)}}
</td>
</tr>

but nothing I tried worked, it always ended up with either a blank response or an error 500. I also tried to add a formula script before save custom script, but that usually just ended in an error too. How can I fix this?