Why is this string not concatenating?

```
@echo off
set NUM_NODES=4
set ENSEMBLE=127.0.0.1:2181

for /l %%x in (2, 1, %NUM_NODES%) do (
    echo %%x
   set ENSEMBLE=%ENSEMBLE%,127.0.0.1:2%%x81
)
echo ensemble: %ENSEMBLES%

```

OUTPUT:

```
2
3
4
ensemble: 127.0.0.1:2181,127.0.0.1:2481

```