Query to extract unique values from 1 column and add matching numeric values

I have multiple sets of 2 columns (COL_LEFT and COL_RIGHT) and would like to extract all the unique values (except the blanks) from COL_LEFT and display matching values from COL_RIGHT alphabetized by COL_LEFT values. If values in COL_LEFT are duplicates, I would like the final COL_RIGHT to show the sum of all values.

My query formula fails, please see the example with the problem and desired output:https://docs.google.com/spreadsheets/d/1-aXqlYmamPI7QKad4qxacVRrC9Q6uKdDdNDUjJOvrak/edit?usp=sharing

Thank you