Template error when I use variables in lang tags

[goldmorphin]

Hello! I have weird problem with this code:

{{foreach $user['general'] as $key => $array}}

<h3 class="ipsType_sectionHead ipsSpacer_bottom ipsSpacer_half">{lang="api_{$key}"}</h3>

<table class="ipsTable">
  <tr>
    <th>Name</th>
    <th>Description</th>
  </tr>
  {{foreach $array as $param => $value}}
  <tr>
    <td>
      <code>{$param}</code>
    </td>
    <td>{$value}</td>
  </tr>
  {{endforeach}}
</table>
{{endforeach}}

when I'm try to use {lang="api_{$val}"} - its working for <h3> element and I see translated text, but next foreach doesn't work and all rows is empty.

But when I put something like:

<h3 class="ipsType_sectionHead ipsSpacer_bottom ipsSpacer_half">{$val}</h3>

all code in template is working fine. Why it's happening? What I'm doing wrong?

[bfarber]

For testing, try

{{$key = "api_" . $langKey;}}
{lang="$key"}

Without firing up a test instance it's hard to confirm, but interpolating the { and } inside the plugin tag may be confusing the template parser.

[Aiwa]

I'd first check your data structure you're looping through. I'm doing something almost exactly the same, and it works without issue. 

{{foreach $member->bf4 as $plat => $data}}
				<li class="ipsMenu_item">
					<a href="{url='...' csrf='true'}">
						<span>{lang="bf4_{$plat}"}: {datetime="$data->last_update" short="TRUE"}</span>
					</a>
				</li>
				{{endforeach}}