[SI-731 - SI-2451] modifications from test

Signed-off-by: Peter Buschmann <peter.buschmann@pta.de>
diff --git a/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group-member-postcodes/distribution-group-member-postcodes.component.html b/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group-member-postcodes/distribution-group-member-postcodes.component.html
index 5071caa..c0cca8b 100644
--- a/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group-member-postcodes/distribution-group-member-postcodes.component.html
+++ b/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group-member-postcodes/distribution-group-member-postcodes.component.html
@@ -23,15 +23,15 @@
       class="form-control"
       placeholder="{{ 'DistributionGroupMemberPostcodes.Postcode' | translate }}"
       onkeypress="return event.charCode >= 48 && event.charCode <= 57"
-      [disabled]="sandbox.disableMemberButton"
+      [disabled]="sandbox.disableMemberButton || sandbox.getDistributionGroupMemebers().length === 0"
     />
     <button
       type="button"
       class="btn btn-primary btn-sm postcode-btn"
-      [disabled]="sandbox.disableMemberButton"
+      [disabled]="sandbox.disableMemberButton || sandbox.getDistributionGroupMemebers().length === 0"
       (click)="assignPostcode(postcodeInput.value); clearPostcodeInput()"
     >
-      <i class="fa fa-plus"></i>
+      <i class="fa fa-plus postcode-icon" style="margin-left: 0px"></i>
     </button>
   </div>
 </div>
diff --git a/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group.sandbox.ts b/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group.sandbox.ts
index c60e386..16b3c06 100644
--- a/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group.sandbox.ts
+++ b/projects/grid-failure-information-app/src/app/pages/distribution-group/distribution-group.sandbox.ts
@@ -357,6 +357,10 @@
     }
   }
 
+  public getDistributionGroupMemebers(): Array<DistributionGroupMember> {
+    return this._distributionGroupMembers ? this._distributionGroupMembers : [];
+  }
+
   private _updateMember(postcodes: PostcodeInterface[]) {
     let postcodeStringArray: string[] = [];
     if (postcodes.length > 0) {