AutoCompleteTextView doesn't show the text bar

Question

I've an AutoCompleteTextView in my Layout, the problem is that although it works perfectly, the "text bar" (I don't know really how it's called "|") is not shown, so it's a bit hard to know where is the focus. Do you know how can I fix it?

<AutoCompleteTextView android:id="@+id/a_addproduct_producto_text" 
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:singleLine="true" android:imeOptions="actionNext"
                android:background="@android:drawable/editbox_background_normal" 
                android:cursorVisible="true"
                android:textColor="@android:color/black"
                android:textSize="17sp"/>