If the Refresh Chart command is "greyed out" (meaning you can't click it), it usually means the chart of accounts is locked to prevent changes.
If you need to use Refresh Chart, you can unlock the chart of accounts as described below.
How did the chart of accounts get locked?
The easiest way for this to occur without realising it is when you make a change in the Maintain Chart of Accounts window, such as changing chart code, description, GST I.D. etc. On exit you will be asked "You have altered the client's chart. Do you want to lock the chart to prevent it being refreshed?"
If you click Yes to this question then the Lock Chart of accounts option will be enabled.