the VFSubState in this library cannot find all the isomorphic subgraphs？

[cwjmusic]

Can the algorithm in this library find all the subgraphs that are isomorphic to the input file?I've just input a datagraph which has about 10000 node and 6000 edge,but I find that the VFSubState algorithm cannot find isomorphic subgraphs in most time, Is that means this algorithm cannot be used in this large dataset?
And if I use the datagraph has only 1000 node.In some case it also cannot find result while the isomorphic subgraph is trully exist.
Could you please give me some advise?