Ext JS 5 Button.sass error onbuild - sass

Question

I am trying to make my own template in Ext JS 5, I use desktop view.
I followed this guide http://docs.sencha.com/extjs/5.0/core_concepts/theming.html Everything is clear to me; I make a new template, default scss works very well, but when I try make a Button.scss file, something like this:
#include extjs-button-ui(
$ui: 'team-arrow',
$background-color: red
);
and try to build an application by 'sencha app build' I get this error:
[INF] executing compass using system installed ruby runtime
error UbiPlatformPBX-all.scss (Line 62 of ../../../../../ext/packages/ext-theme-base/sass/etc/functions.scss: Undefined operation: "5px-null gt 0".)
create UbiPlatformPBX-all.css
[ERR]
[ERR] BUILD FAILED
[ERR] com.sencha.exceptions.ExProcess: compass process exited with non-zero code : 1
[ERR] at co
[ERR] m.sencha.command.Sencha.dispatch(Sencha.java:72)
[ERR]
[ERR] Total time: 19 seconds
[ERR] The following error occurred while executing this line:
/usr/local/ubipbx/wc_patryk/ubiquity-platform/extjs/.sencha/app/build-impl.xml:284: The following error occurred while executing this line:
/usr/local/ubipbx/wc_patryk/ubiquity-platform/extjs/.sencha/app/sass-impl.xml:155: The following error occurred while executing this line:
/usr/local/ubipbx/wc_patryk/ubiquity-platform/extjs/.sencha/app/sass-impl.xml:176: com.sencha.exceptions.ExProcess: compass process exited with non-zero code : 1
I have no idea what the problem is, for example when I make a Panel.scss file and use this code:
#include extjs-panel-ui(
$ui: 'highlight-framed',
$ui-header-background-color: yellow,
$ui-border-color: yellow,
$ui-header-border-color: yellow,
$ui-body-border-color: yellow,
$ui-border-width: 5px,
$ui-border-radius: 5px
);
everything works ok.