TeamCity can't load mstest result

I use ANT to execute mstest and echo "teamcity[importData type='mstest'" to tell TeamCity to load mstest result file.

However, recently, roughly about 50% of the chances the line will be split into two:

[18:55:40]: [exec] ##teamcity[importData typ
[18:55:40]: [exec] e='mstest' path='O:\BuildAgent\work\b0b5fa408cbb6f84\test\dotnet\teamcity.test.trx']

And TeamCity is not able to recongize the importData.

Any suggestions on how I can improve this situation?

sam