tabcontrol event fired automatically

hi,
in my webform i created 2 textboxes(txtcallerid,txtalternatecallerid) and one tabcontrol contain two tab pages(tabpageone,tabpagetwo).
for txtalternatecallerid i fired keyup event when i press enter.
 in tabpagetwo(tabcontrol) i placed one textbox(txtid) and one button(btnsearch).
my problem is ...
now i am focus in tabpagetwo(tabcontrol) txtid textbox. again  i am moving to txtalternateid textbox in main form and enter phone number and press enter key.
at that time in tabpagetwo(tabcontrol) button(btnsearch) event called automatically.
how to solve this proble...
plz tell me solution.......