First, you're going to need to submit a false positive report:
https://submit.symantec.com/false_positive/
After that is done, you will need to open a case with and work with technical support on this. At the very least, you need to get a case number. Symantec employees frequent the forum so one of them can assist if you have a support number they can take a look at it. Since your binary is signed I wouldn't expect this to be flagged as it is one of the requirements that needs to be met in order for it to be considered legit. Support should definitely look into this.
You can also submit your software to get it added to their whitelist:
https://submit.symantec.com/whitelist/
Brian