st: bootstrap gives errors with -rd-

[D-Ta <altruist81@gmx.de>]

Dear Stata Users,

I have the following problem.

I use the -rd- command to estimate a local effect of  (a treatment) X on 
outcomes Y (several ouotcomes, some binary and some continous) at Z=0 in 
the following way:
bootstrap, rep(200) : rd Y X, n(50)

where X=1 if Z>=0 and X=0 if Z<0.

Z takes the values: -12 , -11.5, -11, .... ,-0.5, 0, 0.5, 1, ...,12
Around the cut-off value I have 15-20 observations in each category of Z.

When I run the command I get a lot of bootstrap replications that fail 
(red X). This is more so for binary outcomes! I also tried to use 
-bootstrap, strata(Z) rep(200)-  but the problem remains.
Can someone explain what I do wrong?


Many thanks

Darjusch
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