I am trying to download/export responses to an assessment form in forms central and also the summary report. I have tried saving it as excel and also as PDF. In both instances I keep getting the following message: "Acrobat.com could not save this file.

I am trying to download/export responses to an assessment form in forms central and also the summary report.  I have tried saving it as excel and also as PDF.  In both instances I keep getting the following message: "Acrobat.com could not save this file. The file might be open in another application and cannot be overwritten."  Since I have several assessment forms, I made sure they were all closed and it still will not export/downloard the responses or the summary report.  Please tell me what else to do as I nee these responses and summary reports for our organizations files.  Thank you