When you try to add value to just one or two columns and not all the columns of the table, then you have to mention that in order and specify its values in that order too in your INSERT statement, which you are missing.
strSql = "INSERT INTO MainTable(COMPANY_COLUMN_NAME) VALUES('" & Company & "')"
Regarding the error that you might have faced while trying to add values for all the columns, check if all VARIABLES are having values.
Also check this Page -
Why do I get an 0x80040e14 error message? that deals with other errors of similar error code.
Hope that helps.
Cheers!
_________________________
- Vijay G
Strive for Perfection