What state is the application in? Is it a compiled version (MDE/ACCDE) If so Access reports undefined errors all the same way. Unlike an MDB it will say for example Invalid Use Of Null as the actual error, whereas the compiled version knows that an error has occurred but does not clearly know what is at fault only that an error occured when you click the button.
Thus becoming a generic error. Try in the mdb /accdb state to identify the error then trap it.