Hello,

I am new at the synth command. I am using Stata 15. I want to estimate a treatment effect using the synthetic control method with the code:

Code:
synth m regulated, trperiod(651) trunit(1)
and I received the outpud:

Code:
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Synthetic Control Method for Comparative Case Studies
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First Step: Data Setup
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treated unit: for 1 of out 1 units outcome variable m is missing in 684 results period - check resultsperiod()
invalid syntax
r(198);
could someone help me to understand what is wrong with the command and how to solve it?

Thanks.