Error on creation of sum in write table

Hello,
I am trying to create a sum of arithmetic columns in a writer table, using
the procedure described in the help document. I put the cursor into the
cell that the sum should end up in, press F2, then select the first cell
that is part of the sum (eg. <C2>) and then drag the mouse down to the last
cell (eg. <C12>). When I press "enter" The procedure creates "=SUMME<C2:C12>",
which seens to be correct to me. Nevertheless I get the error "** Fehlerhafter
Ausdruck **" (=erroneous expression). What am I doing wrong?
Thanks for your help
H. Stoellinger

=SUMME(<C2:C12>) with braces.