closing another file by code causes failure to run workbook activate event

I have a userform in workbook A that opens workbook B and hides the userform. File B has a button to "return to the userform (workbook A)". All the button does is close workbook B, which should activate workbook A and trigger the reshowing of the original userform; but the activation event doesn't trigger and the form does not reshow, but wb A is the active workbook. If I close workbook B with the x or file close command, workbook A is activated and the activation code runs, triggering the redisplay of the userform. All the code does is

ThisWorkbook.Close

It actually used to do a lof of other stuff, but, I can't get it to work with just this line. Something is different about closing the form from this one line macro, and closing through file close, I think. Can anyone shed any light on what is going on, and perhaps provide an alternate method?

I have also tried leaving wb B open, then close it when wb A is closed through the userform termination event. Wb A closes fine that way, but, if closing wb A is preceded by the closing of wb B in the userform termination code, the code stops after closing wb B and leaves wb A still open. Basically, when the userform is closed, I want both files to be gone; and I can't seem to get it done.

Thanks

Ken