Sorry if this question is simple but I have googled and haven't found a satisfactory answer.
I'm creating an engineering cost estimator. I have a form that takes inputs as ISO/Drawing, and for each drawing number are many subforms where you can input ComponentDesc and should spit back out a TotalHours to complete number. I've included a picture (sorry for bad quality)
From the image, the table on the bottom is a subform in datasheet mode (which is usually hidden and located in the footer) which will calculate appropriate Total MH (manhours) for the ComponentDesc inputted into the subform on the right. I would like the small (and incomplete) textboxes to the left (below the title "MH Totals for ISO/Drawings") to display the aggregate total from the subform on the bottom.
I've been trying to use DSUM() to define Control Source for the textbox but it keeps coming back with #ERROR as seen in the textbox to the left. Right now what I have typed out is:
=DSum("[Total MH]","frm-PipingHandleMH")
in the expression builder. [Total MH] being my field and frm-PipingHandleMH being the subform on the bottom. I've tried to put brackets around everything but it didn't work (even though I'm not exactly sure what brackets usually do). Any advice?