XML : Binary XML file line #23: Error inflating class com.example.caesar.library.ChipView

i have an error which i cant seem to solve. this is my XML activity_main. this is line 23. com.example.caesar.library.ChipView i dont know what the problem is since the library can be found. the app runs perfectly but crashes as soon as it hits the emulator.

  <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:chip="http://schemas.android.com/apk/res-auto"      xmlns:tools="http://schemas.android.com/tools"      android:layout_width="match_parent"      android:layout_height="match_parent">        <LinearLayout          android:layout_width="match_parent"          android:layout_height="match_parent"          android:orientation="vertical"          android:paddingBottom="@dimen/activity_vertical_margin"          android:paddingLeft="@dimen/activity_horizontal_margin"          android:paddingRight="@dimen/activity_horizontal_margin"          android:paddingTop="@dimen/activity_vertical_margin"          tools:context=".MainActivity">            <TextView              android:layout_width="wrap_content"              android:layout_height="wrap_content"              android:layout_marginBottom="4dp"              android:text="@string/default_chip" />            <com.example.caesar.library.ChipView              android:id="@+id/text_chip_default"              android:layout_width="match_parent"              android:layout_height="wrap_content" />            <TextView              android:layout_width="wrap_content"              android:layout_height="wrap_content"              android:layout_marginBottom="4dp"              android:layout_marginTop="20dp"              android:text="@string/attrs_chip" />            <com.example.caesar.library.ChipView              android:id="@+id/text_chip_attrs"              android:layout_width="match_parent"              android:layout_height="wrap_content"              chip:chip_background="@color/deep_orange"              chip:chip_background_selected="@color/blue_grey"              chip:chip_corner_radius="6dp"              chip:chip_line_spacing="20dp"              chip:chip_padding="10dp"              chip:chip_side_padding="10dp"              chip:chip_spacing="16dp" />          <!-- chip:chip_background_res="@drawable/chip_selector" -->            <TextView              android:layout_width="wrap_content"              android:layout_height="wrap_content"              android:layout_marginBottom="4dp"              android:layout_marginTop="20dp"              android:text="@string/with_layout" />            <com.example.caesar.library.ChipView              android:id="@+id/text_chip_layout"              android:layout_width="match_parent"              android:layout_height="wrap_content" />            <Button              style="?android:attr/buttonStyleSmall"              android:layout_width="wrap_content"              android:layout_height="wrap_content"              android:text="Add"              android:id="@+id/button"              android:layout_gravity="right"/>            <EditText              android:layout_width="match_parent"              android:layout_height="wrap_content"              android:id="@+id/editText" />            <TextView              android:layout_width="wrap_content"              android:layout_height="wrap_content"              android:layout_marginBottom="4dp"              android:layout_marginTop="20dp"              android:text="@string/with_override" />            <com.example.caesar.library.ChipView              android:id="@+id/text_chip_override"              android:layout_width="match_parent"              android:layout_height="wrap_content" />      </LinearLayout>  </ScrollView>