created new vlan on cisco 3560g - devices not recieving IP address

Hello all and thanks for your time and expertise.
Here's my scenario:  The network in the building I'm working on is flat (on the default vlan 1.)  There are three switches, all cisco 3560gs.  We have the core switch, the mdf, and one idf.  
- I wanted to segment all of the wireless traffic on a new vlan (10) .  On the core, I created the vlan and named it.  I also assigned it an ip address and subnet, and ip helper address.
- I then wanted to trunk all of the ports the APs are plugged into.  I configured the AP ports are as follows:
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk allowed vlan 10

- I created the corresponding dhcp scope for the wifi devices.  
- when i execute sh vlan on the core, mdf, or idf - my new vlan shows up so vtp is working.
- when i execute sh int trunk (relative to the ap port trunked) - it show the trunk port and my allowed vlan.
Anyway, as I indicated - my wifi devices are not getting an ip address on this new vlan.  Please let me know if there's something I'm missing.  This is a flat network and I'm now adding a vlan.  Your help and recommendations are greatly apprecaited.
pendal1IT ManagerAsked:
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arnoldCommented:
Do you have an option to test DHCP client as well as checking the DHCP server dealing with whether the DHCP packets from the clients are making their way for ugh the helper to the DHCP server. The other is whether the DHCP server when receding the forwarded DHCP packets has a scope to which they apply defined.

Simplest way is to connect a single device DHCP on the core switch on a port that is VLAN 10 and see if it gets an IP if not done so already. Trying to eliminate the obvious before hair pulling commences.

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pendal1IT ManagerAuthor Commented:
Thanks arnold.  Yes, I do have a scope configured on my dhcp server that corresponds to the new vlan.  I also have an ip helper defined on the vlan.
The only testing mechanism so far was trunking the port the AP is plugged into and allowing traffic to this vlan.  It's worked in other buildings but they had multiple vlans.
This is the first flat network I've worked in and the first time I created a vlan on a flat network.  And I'm still just a beginner relative to this business.
arnoldCommented:
The issue might be related to the path from the VLAN IP not making it to the DHCP server.

This is why I am suggesting eliminating everything by connecting a DHCP client directly to the VLAN in an effort to eliminate it as the issue before going hunting up the line.
I.e the VLAN IP/segment is it defined

Can you ping the VLAN IP from your LAN? Looking to make sure there is a network path.

First thing to eliminate is that there is no issue in the core  side.

What IP/segment on the new VLAN compared to existing LAN segments?
Can you check on the DHCP server with wireshark/ms network tool to see if it gets a DHCP request from the VLAN
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pendal1IT ManagerAuthor Commented:
Thanks arnold.  Some of those things you recommend will have to wait until Monday.  Hope you will stick with me.  
That said, let's say I'm not able to ping from the idf to the core.  Any ideas what I may be missing in my configuration based on my original post.  Much appreciated.
arnoldCommented:
What are the ACL for VLAN ip crossing.  First would be to make sure the VLAN/ip helper and DHCP server IP segment/scope options are correct and functioning.
Presumably you have a router that feeds, starting on the lower level making sure everything works should resolve the rest since you indicate the Vlan addition propagated up the chain, at this point I think the issue is that either the DHCP forwarded request does not match the defined scope you wish to allocate to the wifi, or the packets does not make it to the DHCP server.
JustInCaseCommented:
Is VLAN 10 configured on all passing devices (switches and routers), and configured necessary trunks ports on those?
switchport trunk allowed vlan 10 - excludes all VLANs except VLAN 10 - some devices need native VLAN to be present on trunks so port can be functional.
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