70D + Tokina 100mm macro problem

A little while ago I upgraded from the 40D to the 70D. Today was the first time I tried to use it with my Tokina Macro lens.

Strangely I am not able to change the aperture in M (the other modes work), it alternates between 5.6 and "L", whatever that stands for.

Any ideas what might be going on?

Heya,

Look in your manual for the word "locked."

Very best,

Oh, DUH! I use that all the time...Let's chalk this up to "severely sleep deprived".

Thanks