Visual C++ Forms problem w/conversion?

[Sophia Olivas]

I am having trouble w/conversion - I have a text box that has a value of type Char that I am looking at to determine which value to pull from an array. If it is F or f it would pull from an array called whole, if it is H or h it will pull from an array called half. I keep getting told that:
1>c:\users\sophia\documents\visual studio 2010\projects\final\final\Form1.h(206): error C2440: '=' : cannot convert from 'System::Double ^' to 'System::Windows::Forms::TextBox ^'
No user-defined-conversion operator available, or
1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

I was told to use wchar_t to convert it and it worked in one spot of the code but it is not working in this part - can someone tell me what I am doing wrong?

 {
 wchar_t convertDuration;
 convertDuration = System::Convert::ToChar(txtDuration->Text);
 
if(txtDuration->Text=="F" || txtDuration->Text=="f")
     txtCharge=whole[lstEquipment->SelectedIndex];
 
else if(txtDuration->Text=="H" || txtDuration->Text=="h")
     txtCharge=half[lstEquipment->SelectedIndex];
 
else
     MessageBox::Show("Incorrect letter entered");
 
 
         }
 

here is the code from the txtCharge

// txtCharge
// 
this->txtCharge->Location = System::Drawing::Point(176, 176);
this->txtCharge->Name = L"txtCharge";
this->txtCharge->Size = System::Drawing::Size(86, 20);
this->txtCharge->TabIndex = 5;
// 
 
 

and here is the code from the txtDuration

// txtDuration
// 
this->txtDuration->Location = System::Drawing::Point(228, 150);
 
this->txtDuration->Name = L"txtDuration";
this->txtDuration->Size = System::Drawing::Size(34, 20);
this->txtDuration->TabIndex = 3;
this->txtDuration->TextChanged += gcnew System::EventHandler(this, &Form1::Input_Duration);
// 
 

This is the code for the arrays:

 
public ref class Form1 : public System::Windows::Forms::Form
{
private:static array <double^>^ half = gcnew[] = {16.0,12.0,20.0};
 
private:static array <double^>^ whole = gcnew[] = {24.0,18.0,30.0};
 
private:static array <String^>^ *equipment = gcnew[] = {"1- Rug Cleaner","2- Lawn Mower","3- Paint Sprayer"};
 
 

I have attached the whole form.h file in case it can help. I have already had to turn this in - so I am just looking to see where I went wrong... so your advice is valuable - but not helping me finish the program for the assignment.