Insert Error: Column name or number of supplied values does not match table definition.

When you wrote your INSERT statement, you used one of two forms:

INSERT INTO myTable (Col1, Col2) VALUES('C1', 'C2')

or

INSERT INTO myTable VALUES ('C1', 'C2')

In the first case, Col1 or Col2 does not exist in myTable, or you have listed two columns and supplied values for three.
In the second, the table does not have two columns.

Use the first version at all times: it guards against changes to the database definition which the second does not.