diff --git a/graph-php.class.php b/graph-php.class.php
index e9bebc1..b3606a0 100644
--- a/graph-php.class.php
+++ b/graph-php.class.php
@@ -2193,7 +2193,7 @@ private function gd_draw_values_y( ){
         $global_min_y = ( isset($this->cfg['global_force_min_y'])?$this->cfg['global_force_min_y']:$this->cfg['global_min_y']);
         $global_max_y = ( isset($this->cfg['global_force_max_y'])?$this->cfg['global_force_max_y']:$this->cfg['global_max_y']);
 		
-        $arr_short_values = $this->long_2_short_arrays( $this->transform_x_values([$global_min_y, $global_max_y ]) );
+        $arr_short_values = $this->long_2_short_arrays( $this->transform_y_values([$global_min_y, $global_max_y ]) );
         rsort( $arr_short_values );
         $count_short_values = count( $arr_short_values );
         $pixels_available = $this->cfg['pix_height'] - $this->cfg['pix_paddingtop'] - 1 - $this->cfg['pix_paddingbottom'] - 1 - $this->cfg['pix_paddinginsidetop'] - $this->cfg['pix_paddinginsidebottom'];
@@ -2639,4 +2639,4 @@ public function compute_offset( $arrval, $accommodate_to_x_samples = 0 ){
         return $tableval;
     } // /compute_offset()
 }// /graph
- ?>
\ No newline at end of file
+ ?>