"Problems with Ping GPRS sample"

Does anyone know what’s wrong?

When I downloaded for first time the ping gprs sample into the Q2687 modem (Dev. Kit) using at+wdwl (after that I reset it using at+cfun=1) then

I run the sample with at+wopen=1

Then
I Execute:

at+gset=1,“empresarial.itelcel.com”,“webgprs”,“webgprs2002”,“0xx.xxx.00x.171”,0,0 to put the PDP Context (This is a fixed IP assigned to the SIMcard)

after that I write and enter:

at+wdata=1,“0xx.xxx.00x.170”,1,400,100,10

The response is:

at+wdata=1,“0xx.xxx.00x.170”,1,400,100,10

Context activation error
ERROR

Can anyone help me solve this issue?