Hi Prudhvi,
There are a number of problems with the tadpole.nex NEXUS file. Make it a data block rather than characters block, parentheses aren't legal in charlabels, I think that you have unintended spaces in some of your charlabels (e.g. 26), and finally, not all of the taxa have the same number of characters, e.g. the second taxon has one fewer.
I didn't check further than that. Fix those issues and we can see what happens from there.
Best,
Derrick