Trigger on selected field change
It seems that to get it to work, you should at least add yet another Rules Conditions, in which you compare the value of your field-request-status field, for both the original value (before editing the field) and the (new) updated value, to verify if they are different.

For a variation of your question, with way more details on this, refer to the accepted answer (disclosure: it's mine ...) to "How to send an email using Rules when a node&#39;s boolean field is changed?".