SmaCC: Shift/Reduce Conflict

Dear all,

I bumped into a conflict while writing a small grammar. Would be  
great to know why. The problem seems to come from the Assignment
I wish to parse the following:
myfunction (a, b, c){
        3 + 10
        var z
        z = 50 + foo()
}

Parser:
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Program : FunctionDefinition * {SPProgram new functions: '1'};

FunctionDefinition :
        Id Arguments "{"
        ExpressionList
        "}" {SPFunction new name: '1'; arguments: ('2' select: [:o| (o  
isKindOf: SmaCCToken) not]); expressions: '4'};

Arguments : "(" ArgumentList ")" {'2'};

ArgumentList : ArgumentList "," Id
                | Id
                | ;

ExpressionList:
        Expression ExpressionList
        | ;
       
Expression :
                FunctionCall
           | VariableDefinition
           | Id "=" ExpressionWithValue {SPAssignment new name: '1';  
expression: '3'}
         | Expression "+" Number {SPAddition new left: '1'; right: '3'}
         | Expression "-" Number {SPMinus new left: '1'; right: '3'}
         | Number {'1'};

FunctionCall :
        Id ArgumentsInCall {SPFunctionCall new name: '1'; arguments: '2'};

ArgumentsInCall :
        "(" ArgumentsListInCall ")" {'2' select: [:o| (o isKindOf:  
SmaCCToken) not]};
       
ArgumentsListInCall :
        ArgumentsListInCall "," Expression
        | Expression
        | ;
       
VariableDefinition :
        "var" Id {SPVariableDefinition new name: '2'};
               
ExpressionWithValue :
         ExpressionWithValue "+" Number {SPAddition new left: '1';  
right: '3'}
         | ExpressionWithValue "-" Number {SPMinus new left: '1';  
right: '3'}
         | Number {'1'};

Number : <number> {'1' value asNumber} ;
Id : <variable> {'1' value asString} ;
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Scanner:
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<number>        :       [0-9]+;
<whitespace>    :       \s+;
<variable> : [a-zA-Z] \w* ;
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Regards,
Alexandre

--
_,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:
Alexandre Bergel  http://www.software-artist.eu
^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.



--
_,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:
Alexandre Bergel  http://www.software-artist.eu
^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.