Problem in ./psql -f /usr/local/pgsql/share/lwpostgis.sql -d database name

Hi,
I have installes POstgresql-8.1.3 and POstgis-1.1.2.
Create Database and Now run POstGIs as follws:

run POstgressql by
su - postgres
.....
./psql -f /usr/local/pgsql/share/lwpostgis.sql -d DataBAseName

Then problem occur as follows: -

BEGIN
psql:/usr/local/pgsql/share/contrib/lwpostgis.sql:44: NOTICE: type
"histogram2d" is not yet defined
DETAIL: Creating a shell type definition.
psql:/usr/local/pgsql/share/contrib/lwpostgis.sql:44: ERROR: could not
load library "/usr/local/pgsql/lib/liblwgeom.so.1.1": libgeos_c.so.1:
cannot open shared object file: No such file or directory
psql:/usr/local/pgsql/share/contrib/lwpostgis.sql:49: ERROR: current
transaction is aborted, commands ignored until end of transaction block
...........


Please resolve it ASAP