Dear Wolfgang and Otared, Thank you for the reply. I have used \setupinteraction[state=start] and open with Adobe Reader already. \StartSteps worked well in \startitemize and \startcombination. For example, \StartSteps \startitemize \item $T(n) =$ \FlushStep \blank[5*big] \item $T(n) =$ \FlushStep \stopitemize \StopSteps ... \StartSteps \placefigure[none][]{} {\startcombination[3*1] {\externalfigure[TriNo60][width=.3\makeupwidth]}{\FlushStep} {\externalfigure[TriNo90][width=.3\makeupwidth]}{\FlushStep} {\externalfigure[TriNoDbl][width=.3\makeupwidth]}{\FlushStep} \stopcombination} \startformula T(n) = n(n+1) \over 2 \stopformula \FlushStep \StopSteps But I couldn't make it work with lines of formulas. I think that it is not working with \NC, \NR structure. I'll try t-rsteps and thank you for the file. It is another good way to make slides. Thank you. Best regards, Dalyoung