problem after adding 10th volume

nice plugin, monitoring two RS3412, until today without problems. today added another volume (the 10th) and script says now:
./check_snmp_synology: line 307: 49
.1.3.6.1.2.1.25.2.1.4
/volume10
4096 Bytes
438650334
648744698
3576310 * 100 / 49
.1.3.6.1.2.1.25.2.1.4
/volume10
4096 Bytes
1032116978
438650334
3576310: syntax error: invalid arithmetic operator (error token is “.1.3.6.1.2.1.25.2.1.4
/volume10
4096 Bytes
438650334
648744698
3576310 * 100 / 49
.1.3.6.1.2.1.25.2.1.4
/volume10
4096 Bytes
1032116978
438650334
3576310”)

tried to find on myself, but as not a programer, no chance.. 🙂 any help very appreciated,
regards martin