Can't use toolbox

Hi,

I want to run the code：

clear
clc
syms k
y = symsum(k^2,k,0,10)

but the result says：

'syms' requires Symbolic Math Toolbox.

I back to check my download and use "ver",

the result shows there is Symbolic Math Toolbox.

Does there is anything wrong?

Thank you very much!

[Rik]

You could try

rehash toolboxcache