[mrtg] Problem with external get

[erichter at dds.nl]

I have a program to make the number of mail messages availeble to mrtg. The
output looks:
5
9

<5> is the number on server 1
<9> is the number on server 2

Th part of the cfg:
Target[mail-queue]: `/usr/local/mrtg/bin/queuestats`
MaxBytes[mail-queue]: 150
Options[mail-queue]: gauge, nopercent
Title[mail-queue]: Aantal berichten in mailqueue's
PageTop[mail-queue]: <H1>Aantal berichten in mailqueue's</H1>
WithPeak[mail-queue]: dwmy
YLegend[mail-queue]: No. of messages
ShortLegend[mail-queue]: messages

While running mrtg, this error occurs:
Problem with Externale get '`/usr/local/mrtg/bin/queuestats`':
   Expected an INTEGER for 'in' but got ''

Can anyone tell me the thing I'm doing wrong?
(using 2.8.6)

Eric

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