Question: Use of Heaviside Function

I'm having difficulties in using the Heaviside function in Maple. My heaviside function is (t-tau), and I'm having trouble integrating tau from zero to t. After integration, the expression still shows an integral. Is it because when tau = t, the heaviside becomes zero? Any and all help is appreciated. Attached is the actual sheet. The 2nd to last and last steps are the steps or concern.... **** This problem has been overcome *****
Please Wait...