diff --git a/src/main/kotlin/main/VpcSpigotIntegration/SignHandler.kt b/src/main/kotlin/main/VpcSpigotIntegration/SignHandler.kt
index 684b651..cc56e89 100644
--- a/src/main/kotlin/main/VpcSpigotIntegration/SignHandler.kt
+++ b/src/main/kotlin/main/VpcSpigotIntegration/SignHandler.kt
@@ -94,7 +94,12 @@ class SignHandler: Listener {
         LOGGER.info("Container block: $cordX $cordY $cordZ")
 
         val container: Chest = containerBlock.state as Chest
-        val firstItem = container.blockInventory.contents[0]
+        LOGGER.info("Content: ${container.blockInventory.contents}")
+        var firstItem = container.blockInventory.contents.filterNotNull().firstOrNull()
+        if (firstItem == null) {
+            Utils.send(event.player,"&cВ контейнере нет предметов для покупки.")
+        }
+        firstItem = firstItem as ItemStack
         LOGGER.info("firstItem: ${firstItem.type} | amount: ${firstItem.amount}")
 
         // Get info
@@ -150,7 +155,7 @@ class SignHandler: Listener {
 
             var coloredLine: String
             // Check if some data is missing
-            if (vpcUsername.isEmpty() || cost == null || amount == null) {
+            if (vpcUsername.isEmpty() || cost == null || amount == null || amount < 0 || cost < 0) {
                 coloredLine = ChatColor.translateAlternateColorCodes('&', "$PREFIX&cError")
                 event.setLine(0, coloredLine)
                 return
diff --git a/src/main/kotlin/main/VpcSpigotIntegration/VpcServerIntegration.kt b/src/main/kotlin/main/VpcSpigotIntegration/VpcServerIntegration.kt
index 67eec6f..2368b0c 100644
--- a/src/main/kotlin/main/VpcSpigotIntegration/VpcServerIntegration.kt
+++ b/src/main/kotlin/main/VpcSpigotIntegration/VpcServerIntegration.kt
@@ -712,10 +712,12 @@ pay_by_sign=${DEFAULT_PAY_BY_SIGN}
 								val availableAmount = paymentInfo.container.inventory.all(type).values.sumOf { it.amount }
 								if (availableAmount < paymentInfo.amount) {
 									LOGGER.error("Not enough items after pay invoice, try to return VPC...")
+                                    Utils.send(paymentInfo.player, "&cВ контейнере недостаточно предметов, попытка вернуть VPC...")
                                     val vpcUsername = DataManager.getPlayerVPCUsername(paymentInfo.player.name).toString()
                                     val transferResult = VpcApi.transfer_coins(vpcUsername, paymentInfo.cost).toString()
                                     if (transferResult != "OK") {
                                         LOGGER.error("Can't return VPC, result: $transferResult")
+                                        Utils.send(paymentInfo.player, "&cНевозможно вернуть VPC, обратитесь к администратору: $transferResult")
                                     }
 								} else {
 									// If we have needed items