[maxmsp] "script send ..." does not work for strings

I try to set the text of a message box via [thispatcher] but the box does not react. I can hide and show objects and set values (also with "send"), but not send a single word.

The command is simple, so I do not know what could be wrong:
script send lfo_param3_title Phase
... which should put the word "Phase" into the message box "lfo_param3_title".

At the moment I use [umenu] as a workaround but maybe someone can tell me what can be wrong.
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Peter