[Maxima] Product - strange behaviour

[Walter Wegscheider]

I tried to compute

(%i1) product(3*k,k,1,n), simpproduct;
Nothing happens - MAXIMA delivers only the input instead of 3^n*n!

But:
(%i2) product(3,k,1,n), simpproduct;
(%o2) 3^n
(%i3) product(k,k,1,n), simpproduct;
(%o3) n!

Why is Maxima able to compute all parts, but not the whole given product?

Thank you very much for more insight. 
Walter Wegscheider
PH-NOe, www.austromath.at