Hi! I'm writing some MathCAD 14 worksheets that are ActiveX friendly and can be used with my LabVIEW program. I'm trying to add some flexibility to the worksheet, so that an end-user can use the worksheet as is and I can consume data from using LabVIEW as well. From LabVIEW I'm passing my data to a 2d matrix I call "LV_InArray" in my worksheet. If LabVIEW is not using the worksheet, then LV_InArray results in an error ("This variable is undefined.". I want my worksheet to work if the user is using it directly in MathCAD, and it to work if LabVIEW is using it through ActiveX. Surely there is a way to detect if LabVIEW is using the worksheet or not and set variables appropriately. Attached is what I have tried. As you can see, "on error" does not appear to resolve that LV_InArray is not present (and therefore errors) and the 3x3 matrix is not being taken instead of the erroneous LV_InArray variable. What is going on here? How can I catch an error the way I want to?