Personal Campaign Pages don't have a donate button
Looking at the code, I can see that the donation button only appears if $validDate is TRUE and $contributeURL is TRUE.

Enable debugging (Administer menu > System Settings > Debugging and Error Handling, select "Yes" to "Enable Debugging"), then reload your PCP page, adding this to the end of the URL: &amp;smartyDebug=1.  You'll get a pop-up showing all your Smarty variables.  Make sure that there's a value for both $validDate and $contributeURL.

My guess is either:


You're before the PCP begin date;
You're after the PCP end date;
Your server has the wrong time set.


PS - also make sure there's a value set for $contributionText.  You can set this by editing the PCP and filling in the value for "Donation Button".