XML : Android: Grid Layout Uneven Column Spaceing With ColumnSpan

I'm fairly new to android's xml but I have been having some trouble with the grid layout. All I want is for all the buttons in a grid to be evenly spaced from each-other with the two top center most buttons sharing a border. This is the code I have so far:

  <GridLayout      android:layout_width="match_parent"      android:layout_height="wrap_content"      android:columnCount="4"      android:rowCount="5"      android:alignmentMode="alignBounds"      android:layout_weight="1">        <LinearLayout          android:id="@+id/select_box"          android:layout_width="wrap_content"          android:layout_height="wrap_content"          android:layout_column="1"          android:layout_row="0"          android:layout_columnSpan="2"          android:layout_gravity="top"          android:layout_columnWeight="0"          android:background="@drawable/selected_border_one">            <Button              android:id="@+id/selected_text_one"              android:layout_width="0dp"              android:layout_height="match_parent"              android:layout_weight="1"              android:layout_gravity="center"              android:text="TYPE 1"              android:textColor="@color/trueBlack"              android:background="#999999"              android:onClick="selecSelection"> </Button>            <Button              android:id="@+id/selected_text_two"              android:layout_width="0dp"              android:layout_height="match_parent"              android:layout_weight="1"              android:layout_toRightOf="@id/selected_text_one"              android:layout_gravity="center"              android:text="TYPE 2"              android:textColor="@color/trueBlack"              android:background="#555555"              android:onClick="selectSelection"> </Button>        </LinearLayout>        <Button          android:id="@+id/ground_but"          android:layout_width="0dp"          android:layout_height="0dp"          android:layout_row="4"          android:layout_column="0"          android:layout_columnWeight="1"          android:layout_rowWeight="1"          android:layout_gravity="fill"          android:background="@color/groundBrown"          android:text="@string/ground_string"          android:onClick="setType"/>             ... Rest of the buttons    

The outcome of this is: can be seen at http://i.imgur.com/r4FGM4C.png because apparently since my account is new I cant post images.

As you can see (assuming you looked at the picture) the third column is taking over some of the second column's space. If I remove the linear layout holding the two buttons with the border then everything is spaced properly, but I can't figure out why adding it in changes the weights. Any help will be greatly appreciated and thank you in advanced.