st: problem with placevar

This is my problem:

. placevar fuma811,after(fuma812)
str52 not allowed
r(101);

fuma811 and fuma812 exist, the problem is with someone. Any placevar give the same error

Could you hemp me, please????

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References:
- st: syntax -chi2fit-
  - From: "Rajiv Mallick" <[email protected]>