if blocks

I’ve got a field slider_1and I trie to show in a template but only if the field is not empty. something like this:

[if slider_1]
<li><img src="{@slider_1._src}" /></li>
[/if]

but the result is:

<li><img src="" /></li>

https://www.ads-software.com/plugins/pods-frontier-auto-template/