merging segment and annual data from Compustat

[fred finn]

Hello everyone.
I am writing a research paper where I will look at the difference between US firms with foreign operations versus US firms with purely domestic revenue stream.
However, to do so I need to merge my segment data file with my annual data file (master file).
The command I write is: "merge 1:1 gvkey datadate using (segment data location)"
I seem to get the message "variables gvkey datadate do not uniquely identify observations in the master data" I have tried with 1:m merge and m:1 merge as well. If anyone could help me merge the two data sets, it would be highly appreciated.

Fred

Edit: here are screen dumps of how the datasets look like.

[Carlo Lazzaro]

Fred:
what if you

rename revts revt//in both files

and try

[CODE]merge 1:1 gvkey revt using (segment data location)/[CODE]

[fred finn]

Thank you for your quick reply Carlo. I tried what you suggested, but I still get the message variables gvkey revt do not uniquely identify observations in the master data. I think the reason is because the Segment database creates several revenue posts for the same Date Year, one per Geographic segment. Which means that if a company has operations in 4 different country segments, it will post revenues for all of these in each year. I do not know how to solve this. What would be optimal would be to separate these "double posts" by sumarizing the foreign revenues per year as its own variable.