This issue appears when (for example) an MS Access database has spaces in table names. From 'Database Structure' panel, right-click on table >> Generate Select Statement. Resulting statement appears in editor, like this:
select site, start_date, method, site marker, head open, head cap, head value, casing shoe, bullnose cap, airline depth, pump depth from Fittings
The table names should be enclosed in square brackets: [site marker], etc.