If Launchpad rejects an upload to your PPA with the message
Rejected: Source/binary (i.e. mixed) uploads are not allowed.
it’s because Launchpad only wants the source package and you have also build a binary package. Just add the -S parameter to your build command to have a source-only build.
After uploading the files Launchpad will use its build farm to build the binary packages. This usually takes about two hours but can also take much longer for some architectures.