There are several problems that can cause such behavior :
This error occurs when you try to use a special character in a SQL statement. If a special character other than $, _, and # is used in the name of a column or table, the name must be enclosed in double quotations.
This error may occur if you've pasted your SQL into your editor from another program. Sometimes there are non-printable characters that may be present. In this case, you should try retyping your SQL statement and then re-execute it.
This error occurs when a special character is used in a SQL WHERE clause and the value is not enclosed in single quotations.