Using variables to add and subtract a number in a text field?

The adding bit works fine:

// get this pconn count

var this_p_conn:Number = Object(this).parent.p_conn;

// get current pconn total

var c_this_p_conn:Number = Object(root).part_count.p_conn_count.text    

// add this pconn count to total pconn

var v_this_p_conn:Number = Number(this_p_conn+c_this_p_conn);

// Update total pconn with new value

Object(root).part_count.p_conn_count.text = String(v_this_p_conn)

Removing a value from the total is another story, this looks like it should work but it does not:

// get this pconn count

var count_p_conn:Number = Object(this).parent.p_conn;

// get current pconn total

var total_p_conn:Number = Object(root).part_count.p_conn_count.text;

// subtract this pconn count from total pconn

var new_p_conn:Number = Number(total_p_conn-count_p_conn);

// Update total pconn with new value

Object(root).part_count.p_conn_count.text = String(new_p_conn);

Any ideas or suggestions? My eyes are a bit blurry from looking at code, maybe I missed something obvious. Thanks in advance!