The Gospel is good news because of what it saves you from. Without the bad news of sin, children (or anyone, for that matter) are simply asking God to have a part in their lives, to be their friend, to guide them or to do any number of good things for them, but for reasons that don’t address the core problem: God is holy, You and I are sinful. Sin needs to be gotten out of the way.
When counseling children for salvation, watch for signs of concern and sorrow for their sin. If a repentant heart is not evident, it could be a sign that they may not understand about sin and, therefore, their need for a savior or it could be that you may not have sufficiently taught them about sin. Go back over the things they need to know. (See the tip for 7/29/96 - Child-sized Definitions) Remember that it is possible for the child to be genuinely aware of the problem but for it not to show it outwardly. However, it is not as likely for you not to notice a flippant, casual attitude.
Listening and watching for their attitude about sin can be a reflection of the child’s understanding of the Gospel and/or the completeness of your teaching. God wants to do more than just do nice things for them, He wants to save them from something terrible – sin.