assign variable with pipe (Was: variable in save file)

Hi,
I can't assign a variabe with a pipe:
MAILLANG2=`formail -xX-Spam-Possible-Language: | tr 'a' 'b'`
this doesn't work although this works
MAILLANG2=`formail -xX-Spam-Possible-Language: `

mfg Thomas Richter

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