TEXT in selection?

Hi,

does anybody know a way, how to implement the content of a field of type
TEXT
into a query?

if i am trying:
    select  *  from testtable WHERE  testTEXT LIKE '%testString%'

i am getting always an empty selection, although there is a record existing.
The same with

    select  *  from testtable WHERE  position ('testString' in testTEXT) >
0;

Additional, is there a way to use the UPPER()-function to the content of the
TEXT-field?

Thanks in advance,
Michael