Hi @horsemant - I don't think you've done anything wrong here! I'm sorry that my above messages implied otherwise, that certainly wasn't my goal.
Unfortunately the file you uploaded isn't the complete error message - its still missing the first part of it.
I can't say for sure what the issue is that you're observing, but my best guess is that you have a mismatch between the feature IDs in your
FeatureData[Taxonomy] result (you named it
ref-taxonomy-97.qza above) and your
FeatureTable[Frequency] result (you named it
burndada2-merged.qza). Every feature ID in the table must have a corresponding entry in the taxonomy file.
One hypothesis as to why this has happened is that you have provided the wrong taxonomy input here. Recognizing that filenames don't carry any particular meaning to QIIME 2, I do notice that you've used the word "ref" in the filename, which is usually short for "reference." If this is the same convention you have adopted here, then perhaps that's the issue? Usually people use their actual data in these visualizations, rather than a reference database. See this section of the Moving Pictures tutorial for an example.
Let us know if you have any questions. And if you're still running into issue, please make sure to copy-and-paste the entire error message - this takes a lot of the guesswork out of the process.