terminate called after throwing an instance of 'std::logic_error' in TreeMix

Question

[hemr3]

I'm trying to use the programme TreeMix to produce a phylogenetic tree, but this is the input and error:

treemix -i data.p.treemix.gz -o output

terminate called after throwing an instance of 'std::logic_error'
  what():  basic_string::_M_construct null not valid
Aborted (core dumped)

My data looks to be in the proper format, and here is the header:

DEN NEA
2,0 0,2
0,2 2,0
...

The example files worked well so I don't think the programme itself is corrupted. The example file given looks like:

Han Sardinian Colombian Dai French Mozabite Karitiana Lahu BiakaPygmy She Italian San Yoruba 
2,66 2,54 0,10 1,19 4,52 6,48 0,24 2,14 31,13 0,20 3,23 6,6 21,21

The only differences between my data and the example I can think of is the fact that my data only contains 2s and 0s, there are only two populations, and the data overall contains a high level of missingness.

I can't change the programme itself as it is very complex, and as not an adept in C++ yet, I think I'd just muck it up.

I'd be grateful for any advice to help solve this issue!