My heatmap is blank

Nobody has claimed this yet.

I am trying to create a heatmap with the follow data: It is a lot of data points, this is just a preview. Any ideas on why it is blank?
```
TF target importance
0 ZIC5 ZIC2 244.284998
1 DLX6 DLX5 146.211550
2 FOXD4L6 FOXD4L3 139.951544
3 DDX43 OOEP 133.502314
4 FOXD4L3 FOXD4L6 132.367859
5 DLX5 DLX6 131.638314
6 FOXD4 FOXD4L1 128.395748
7 HOXA11 HOXA10 112.056258
8 HOXA2 HOXA3 110.962698
9 ZIC2 ZIC5 109.077028
```

CODE BELOW:
```python
import os
import glob
import pickle
import pandas as pd
import numpy as np
import scanpy as sc
import loompy as lp

from dask.diagnostics import ProgressBar

from MulticoreTSNE import MulticoreTSNE as TSNE

import seaborn as sns
import matplotlib.pyplot as plt

df = pd.read_csv("adj.tsv", sep='\t')
print(df.head(10))
df = df.pivot("TF", "target", "importance")
hm = sns.heatmap(df, linewidth = 0.5, cmap = 'coolwarm')
```

Start with the Python snippet, especially the adj.tsv read, DataFrame pivot, and seaborn heatmap call, and reproduce it in the reported Jupyter setup. The input file and environment details are not provided, so first establish whether the blank output is specific to ipympl. Done means a reproducible diagnosis or a clarified report with the missing setup and data details.

Written by the indexing model from the issue text.