Error: Compile Error: bootstrap-datepicker is not a helper

I am using

https://www.npmjs.com/package/ember-cli-bootstrap-datepicker

package.json in devDependencies:

"ember-cli-bootstrap-datepicker": "0.6.1",

in hbs:

error after ember test:

actual: >
        null
    stack: >
        Error: Compile Error: bootstrap-datepicker is not a helper
            at http://localhost:7357/assets/vendor.js:21757:19
            at Compilers.compile (http://localhost:7357/assets/vendor.js:21369:13)
            at expr (http://localhost:7357/assets/vendor.js:21720:25)
            at http://localhost:7357/assets/vendor.js:21458:17
            at Compilers.compile (http://localhost:7357/assets/vendor.js:21369:13)
            at compileStatement (http://localhost:7357/assets/vendor.js:22127:20)
            at compileStatements (http://localhost:7357/assets/vendor.js:22132:13)
            at CompilableTemplate.compileStatic (http://localhost:7357/assets/vendor.js:22157:31)
            at http://localhost:7357/assets/vendor.js:18256:30
            at AppendOpcodes.evaluate (http://localhost:7357/assets/vendor.js:17481:13)
    message: >
        Died on test #1     at Module.callback (http://localhost:7357/assets/tests.js:1333:24)
            at Module.exports (http://localhost:7357/assets/vendor.js:119:32)
            at requireModule (http://localhost:7357/assets/vendor.js:34:18)
            at TestLoader.<anonymous> (http://localhost:7357/assets/test-support.js:10892:11)
            at TestLoader.require (http://localhost:7357/assets/test-support.js:10882:27)
            at TestLoader.loadModules (http://localhost:7357/assets/test-support.js:10874:16)
            at loadTests (http://localhost:7357/assets/test-support.js:12321:22): Compile Error: bootstrap-datepicker is not a helper
    negative: >
        false
    browser log: |
...

funny fact, if i remove format="dd.mm.yy" from , then it won't throw error. What am i supposed to add or what am i missing to test to work ? package's doc doesn't say anything

edit: i have seen this, ember Error: Compile Error: is not a helper, it seems i have everything right