Select Query Issue with '' data

Execution crashes when parsing the response for a query "select col1,col2 from test", but col1 carries the value as '' (Its just empty quotes, value not set as null).
Problem didn't appear when called as "select col2,col1 from test", where col2 has some string and col1 is ''.
(Note the order of col1 and col2 in both executions).