How to create a bar chart using converted dates to character strings

Jonathan_Thomson_(jonathanthomson_-_(deleted))

Please can you advise how we can produce bar charts where a date is the "STRING" value? Here is my code, but this returns the error that the 1st row must be a STRING value.select SO_date = DATENAME (Month, SO_Date), AVG(100 * SO_SafeTotal / (SO_RiskTotal + SO_SafeTotal)) "Calc1" From IPR_SOGroup BY SO_DateThanks,Jon