[calc] what happened to a i ???

[boffi]

If I try to integrate sin(x) sin(2 x) this is what I get NOW, using
Emacs 25 on Debian and the calc version (?) that is distributed with it

 | --- Emacs Calculator Mode ---
 |       /
 |      | 
 | 1:   | sin(x) sin(2 x) dx
 |      | 
 |     /  
 | 
 |     .
 |

while I'm pretty sure that I've been able to use calc to integrate such
simple expression at some point in the past.

On the other hand, I've installed a very old version of XEmacs and the
corresponding old version of calc and I have

 | --- Emacs Calculator Mode ---
 | 2:  sin(x) sin(2 x)
 | 
 |     2       3
 | 1:  - sin(x)
 |     3
 | 
 |     .
 |

so I'm inclined to think that I've something done something wrong...

Do I have to set some variable to get back the old behavior of calc?

Thank you in advance,
                                                                g