SIL : update text custom field with issuekey of linked issues

[Ashish]

i need to update the text custom fields with the issuekey of issues linked by "implemented by"

My sript :

for(JIssueLink l in getIssueLinksDetail("KD-2")){
if(l.name == "implemented by" && l.direction == -1) {
customfield_10054 = l.id;
}
}

KD-2 is the issue  linked by 

KD-5,ISD-26,KD-3,ISD-35

Script runs without any error , but it does not updates the text custom field

the linked issue KD-5 it has the following properties: 

- link id : 10045

- link name : Design

- direction : -1

- description : implemented by 

[Ashish]

@Alexey Matveev _Appfire_ : Any help please on this topic and where can i learn SIL from

Regards

Ashish