changing value

[abenitez77]

the value of my variable is changing for no reason. I put an alert to check the value of myProjectsID and before I run the if statement, it returns 51. After the if statement it returns 'undefined'. I don't get the alert within the if statement. Why is my value for myProjectsID disappearing?

alert(myProjectsID);
if (myProjectsID == 0 || myProjectsID = undefined)
{
alert("You need to select a project before adding to an existing project");
return;
}
///////////////////////// END TEXTBOX VALIDATION SECTION //////////////////////////////////////////////
alert(myProjectsID);