convert variable to integer and remove unnecessary words

RouterOS Scripting
1

how do I change global to num in order to “work” woth him

/interface ppp-client info [find where comment=ISP1] do={:global SignalISP1 [$"signal-strengh"]};

when I print it I get
-67 dBm
now I did this

global Signal1 value=[:tonum [:pick SignalISP1 ([:find "dBm" -1])]];
log warning message=($Signal1);

but I don’t get any number printed - why ?
I guess I did something stupid and miss something small

Thanks ,

2

I have done something else

/interface ppp-client info [find where comment=pelephone] do={:global pelephone1 [$"signal-strengh"]};
delay 10;
global david value=[:tonum [:pick $pelephone1 0 3 ]];log warning message="Signal is $david"

but he show me that I can’t pick from $pelephone1 - I can see it on red.
why is it?

when I run the command alone in the terminal it’s working