Running command button from another workbook

[DevanG]

Pretty basic. Why doesn't this work? Those are the correct names of the workbook, sheet and sub. Sheet3's is on a tab called VNBData but i didn't think that mattered. I haven't done this with a sub that runs from a command button usually.
Application.Run "'DCM.xls'!Sheet3.cmdvnb_Click"

[Bob Phillips]

Is it an ActiveX button? Is the sheet codename Sheet3?