CheckBox partly visible

I am using a CheckBox in my layout which is partly visible.I am including the screenshot.

Below is the layout and java code.

xml:

<android.support.v7.widget.AppCompatCheckBox

                    android:layout_width="20dp"
                    android:layout_height="20dp"
                    android:text="Check box"
                    android:id="@+id/checkbox"
                    android:theme="@style/MyCheckBox"
                    android:layout_marginRight="40dp"
                    android:layout_marginTop="20dp"
                    android:layout_alignParentRight="true"
                    android:layout_alignParentEnd="true" />

java:

checkbox=(AppCompatCheckBox) findViewById(R.id.checkbox);
        checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

               if(isChecked){
                   relativeLayout.setVisibility(View.VISIBLE);
               }
                else {
                   relativeLayout.setVisibility(View.INVISIBLE);
               }
            }
        });

Screenshot: