Question: Maple 2015 regression...?

I want to solve the following equation for E[k]:

fr = 1.64*10^6*E[k]^2*exp(-8.5/E[k]);

Maple 17 gives

solve(fr = 1640000.00*E[k]^2*exp(-8.5/E[k]), E[k]);

          4.25000000000000             4.25000000000000     
    ----------------------------, --------------------------
            /  5442.65560181792\          /5442.65560181792\
    LambertW|- ----------------|  LambertW|----------------|
            |        (1/2)     |          |      (1/2)     |
            \      fr          /          \    fr          /

Maple 2015 gives:

solve(fr = 1.64*10^6*E[k]^2*exp(-8.5/E[k]),E[k]);
Error, (in solve) invalid input: `evalf/LambertW` uses a 2nd argument, zz, which is missing

This is Maple 2015.2 on OS X 10.10 Yosemite.

I can copy-paste Maple 17's solution into Maple2015 and it evaluates correctly (for a given value of fr).

Is this a bug or am I missing something? Help on LambertW looks identical for both versions of Maple.

M.D.