How to excute dynamically a generated SQL command?

Hi the list,

Referring to the PostgreSQL 8.3 documentation " 38.5.4. Executing Dynamic
Commands ", the command for executing a dynamic command is:
EXECUTE command-string [ INTO [STRICT] target ];

I am to execute an sql statement created dynamically, which is represented
in a variable sSql.
Here is an example:
sSql='INSERT INTO hm_raster.hm_airphotos( file_ext, airphoto) VALUES
('.tif', lo_import( E''C:\\HM\\Data\\Flightmap.tif'');';
EXECUTE sSQL;

It raises the error as:
ERROR: syntax error at end of input
LINE 1: ...E'C:\\HM\\Data\\Flightmap.tif')
^

I would appreciate a lot if you offer your input. Thanks a lot.

John