意味不明の同時エラーを解決したい

#概要
多数Activity型のアプリを製作する途中で、他は順調なものの、実機デバッグした際に見たことないようなエラーが出てきた。
##過程
Activity a(APIなし)　Activity b(APIあり)
a→bの際にエラーが起き、アプリが強制終了。
##エラー文

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.trafficcollector/com.example.trafficcollector.ninsiki}: android.view.InflateException: Binary XML file line #2: Binary XML file line #2: Error inflating class android.support.design.widget.CoordinatorLayout
Caused by: android.view.InflateException: Binary XML file line #2: Binary XML file line #2: Error inflating class android.support.design.widget.CoordinatorLayout
Caused by: android.view.InflateException: Binary XML file line #2: Error inflating class android.support.design.widget.CoordinatorLayout

 Caused by: java.lang.ClassNotFoundException: Didn't find class "android.support.design.widget.CoordinatorLayout" on path: DexPathList

###ソースプログラム
b(APIあり)

java
1package com.example.ninsikikunn;
2//文字数上、importは省略
3public class ninsiki extends AppCompatActivity {
4    private static final String ANDROID_CERT_HEADER = "X-Android-Cert";
5    private static final String ANDROID_PACKAGE_HEADER = "X-Android-Package";
6    private static final int GALLERY_PERMISSIONS_REQUEST = 0;
7    private static final int GALLERY_IMAGE_REQUEST = 1;
8    public static final int CAMERA_PERMISSIONS_REQUEST = 2;
9    public static final int CAMERA_IMAGE_REQUEST = 3;
10    private TextView ocrTextView;
11    private ImageView ocrImageView;
12    @Override
13    protected void onCreate(Bundle savedInstanceState) {
14        super.onCreate(savedInstanceState);
15        setContentView(R.layout.activity_ninsiki);
16        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
17        setSupportActionBar(toolbar);
18        Button selectImg =(Button)findViewById(R.id.selectPhoto);
19        selectImg.setOnClickListener(new View.OnClickListener() {
20//文字数の関係上、省略
21}