if else only executing else in java

so i'm struggling with this problem which seems i cannot understand, im completely new in java and i need help.. so i am making a simple program which will determine if you have passed the subject or not via point grades and it seems it only determines the ELSE STATEMENT.. here's the code.. it will really help me out alot.. thanks in advance

    String studID=" ",course=" ", name=" ", dept=" ", subj=" ";
    double exam1=0, exam2=0, exam3=0, exam4=0;
    double avg, pgrade;
    String msg=" ";

studID =JOptionPane.showInputDialog("Please fill-out the following fields:"
        + "\nStudent ID: ");
name = JOptionPane.showInputDialog("Name: ");
dept = JOptionPane.showInputDialog("Department: ");
course = JOptionPane.showInputDialog("Course: ");
subj = JOptionPane.showInputDialog("Subject: ");
exam1 = Double.parseDouble(JOptionPane.showInputDialog("First Examination: "));
exam2 = Double.parseDouble(JOptionPane.showInputDialog("Second Examination: "));
exam3 = Double.parseDouble(JOptionPane.showInputDialog("Third Examination: "));
exam4 = Double.parseDouble(JOptionPane.showInputDialog("Final Examination: "));
avg = (exam1 + exam2 + exam3 + exam4)/4;
pgrade =(100 - avg + 10) / 10;

if (avg==100)
{
    msg = "passed - Excellent!";
}else if (avg>100 && avg<89)
{
    msg = "Passed - Very Good!";
}else if (avg>90 && avg<84)
{
    msg = "Passed - Average";
}else if (avg>85 && avg<79)
{
    msg = "Passed - Good";
}else if (avg>80 && avg<74)
{
    msg = "Passed - Satisfactory";
}else if (avg>75 && avg<49)
{
    msg = "Failed";
}else if (avg>50 && avg<0.00)
{   
    msg = "Dropped";
}else if (avg==0.00 && avg<0.00)
{
    msg = "No such Grade";
}else
{
    msg = "Out of Range or Invalid.";
}


JOptionPane.showMessageDialog(null, new JTextArea (
        "|======Student Details=======|"
    + "\n|StudentID:\t" + studID +"\t |"
    + "\n|Name:\t" + name + "\t |"
    + "\n|Department:\t" +dept+ "\t |"
    + "\n|Course:\t"+course+"\t |"
    + "\n|Subject:\t"+subj + "\t |"
    + "\n|=======Grade Details======= |"
    + "\n|First     Second     Third     Fourth  |"
    + "\n|"+exam1+"     "+exam2+"     "+exam3+"     "+exam4+"\t     |"
    + "\n|Average:\t" +avg + "\t|"
    + "\n|Point Grade\t:" +pgrade+"\t|"
    + "\n|Remarks:"+msg+"\t|"
    + "\n|=============================|"));





}

}