问android中的类类型转换异常？

EN

wheel = (WheelView) findViewById(R.id.wheel);  

<LinearLayout 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" 
    android:layout_centerInParent="true"
    android:layout_margin="10dip"  
    android:background="@drawable/wheel_side_background">

<com.WheelView  
    android:id="@+id/wheel" 
    android:layout_width="fill_parent"
    android:layout_height="150dip"
    android:layout_marginTop="1dip"
    android:layout_marginBottom="1dip">

Exception:10-10 15:20:17.700: ERROR/AndroidRuntime(720): Caused by: java.lang.ClassCastException: com.skynextech.firstdentalcare.WheelView
10-10 15:20:17.700: ERROR/AndroidRuntime(720):     at com.skynextech.firstdentalcare.PatientSetInfo.onCreate(PatientSetInfo.java:81)
10-10 15:20:17.700: ERROR/AndroidRuntime(720):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-10 15:20:17.700: ERROR/AndroidRuntime(720):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)