"The name 'XXX' does not exist in the current context in .net"

Hi,
Can anybody give me solution for my below query?

"The name 'XXX' does not exist in the current context in .net"

I am able to access the "xxx" control ID in the .cs page but when i compile the page it showing error "The name 'XXX' does not exist in the current context in .net"

Thanks,
gg.