Caldera forms is not calculating hidden fields

Hello,

I created two hidden fields:

subtotal, with value {post:subtotal}
taxas, with value {post:taxas}

<input type="hidden" data-field="fld_3406989" class=" form-control" id="fld_3406989_1" name="fld_3406989" value="214.0000" data-type="hidden"> <input type="hidden" data-field="fld_4754951" class=" form-control" id="fld_4754951_1" name="fld_4754951" value="25.4100" data-type="hidden">

No problem here at all.

So, I created a calculation field with value %subtotal%+%taxas% but the result was zero.

Opening Javascript Console, I can see only this:

jquery-migrate.min.js?ver=1.4.1:2 JQMIGRATE: Migrate is installed, version 1.4.1 parsley.min.js?ver=1.7.2:2 Accessing the method 'addValidator' through Validator is deprecated. Simply call 'window.Parsley.addValidator(...)'

You can test it here:

https://santosmadeiras.com.br/forms/test1/?subtotal=20&frete=2&taxas=5

So, I create variables and retry to doing the calculation using this variables. A this time, the calculation fields work normally, BUT when I try to send the form, I get an error 500:

Parse error: syntax error, unexpected '{' in /home/santosma/www/forms/wp-content/plugins/caldera-forms/classes/core.php(1437) : ru

You can test this second try here:

https://santosmadeiras.com.br/forms/test2/?subtotal=20&frete=2&taxas=5

Anyone can help me, please? :/

Just in time:

[root@vps0693 ~]# php -v PHP 7.0.30-0ubuntu0.16.04.1 (cli) ( NTS ) Copyright (c) 1997-2017 The PHP Group Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies with Zend OPcache v7.0.30-0ubuntu0.16.04.1, Copyright (c) 1999-2017, by Zend Technologies