moving text starts wrongly after clicking on button

Hi

This code must start text moving a number of times according to the value entered in the . The text can only start when 'ronmouseove' event is done over the text, not when the button is clicked. This is what now happens: the text starts moving after clicking on the button by this line: document.getElementById("clem").onmouseover = start(a); But I may as well write something like document.getElementById("clem").xxx = start(a); it also starts.
Any hints? Thanks. V