Substituting Variables into Matricies

I am trying to make substitutions into a matrix using the subs() command, but it does not work.

for example

with(linalg):
A:= matrix([[a,b,c],[d,e,f]]):
B:=subs[inplace](a=1/L,b=-1/L,c=1,d=-1/L,e=L,f=1,A);

                                                                         B:=A

It will not make any substitutions into a matrix or vector and i cant figure out why.  I tried using [inplace] which is

" The inplace option only applies when substituting into an rtable (such as Array, Matrix, or Vector) with no indexing function. When inplace is specified, the input rtable is updated in-place.  The result is the updated original expr rtable, rather than a copy."

Any help is appreciated

Thanks