integral bug in xCas or HP PRIME

[robmio]

Hello everyone. I encountered an error calculating this integral:

int(exp(-s*t)*t*ln(t),t):

xCas or HP PRIME:

Ei((-s)*t)/s^2-e^((-s)*t)*ln(t)/s^2-t*e^((-s)*t)*ln(t)/s

Correct result:

Ei((-s)*t)/s^2-e^((-s)*t)*ln(t)/s^2-t*e^((-s)*t)*ln(t)/s-e^((-s)*t)/s^2

Do you think it's an xCas bug or am I doing something wrong?