Printing more documents to pdfcreator sometimes misses tthe first document


from an microsoft offcie application i try to print a number of pdf files to the pdfcreator, collect them there and combine them into 1 file (the last is done by hand).
I use the follwoing code :

  Shell ("""" & zProg & “”" /t “”" & rcs!Document & “”" PDFCreator “”" & “”"")        'execute command to print  the pdf document

zProg = the path to the acrobat reader
rcs!document = complete path to the file

After the first is being printed i push the wait button for the last document. 
I notice that the first document is not always  arriving in pfdcreator. I’ve tried to add waiting time to the commands, but this does not help.

Is there a better way to do this?