This is the fix for the velocity error estimate, added missing term.

This fix was developed Pasha and approved by the Data Analysis Working Group (DAWG) and recorded as Task#1 on the DAWG webpage.  
https://homepage.usask.ca/~pbp672/Data_Analysis_WG_Task1_DOF_error.pdf
Note: This error was due to the simple typing error which led to significate underestimation of the fitting errors.