integration with infinity limit has problems

[webmasterpdx]

FYI, I also tried assume(a,integer); additionally(a>0);
still got the message.
I was able to use wolfram alpha and didn't have to do anything weird and it gave me the right answer. Like I said, other online forums have said that TI89 and TI-NSPIRE don't seem to have this problem either.
Seems like it's only in the hp prime...
If only I knew what I needed to type in an assume statement or something to achieve the checks it's talking about in the cryptic message.