Hey Flora,
Happy to hear that its working now.
Answering your question, again its upto the connection and report format you are using. Based on your question i hope you your report output should be like this.
You cannot map to two labels for the series, again this report format is possible only in cross tab through Webi. I would suggest you to concatenate the material and month in a dimension in webi like below.
I have done the concatenation in excel level, i would suggest you to do that in webi. Try to reduce the formula as much in excel.
or
If you are using Query browser connection, then i would suggest you to create a separate report which will display the actual vs plan material wise, here you need to pass the material as a prompt.
Hope this helps in clear, please revert me for any clarification.